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In this paper, we propose a new texture descriptor, scale selective extended local binary pattern (SSELBP), to characterize texture images with scale variations. We first utilize multi-scale extended local binary patterns (ELBP) with rotation-invariant and uniform mappings to capture robust local micro- and macro-features. Then, we build a scale space using Gaussian filters and calculate the histogram of multi-scale ELBPs for the image at each scale. Finally, we select the maximum values from the corresponding bins of multi-scale ELBP histograms at different scales as scale-invariant features. A comprehensive evaluation on public texture databases (KTH-TIPS and UMD) shows that the proposed SSELBP has high accuracy comparable to state-of-the-art texture descriptors on gray-scale-, rotation-, and scale-invariant texture classification but uses only one-third of the feature dimension. | Scale Selective Extended Local Binary Pattern for Texture Classification |
Neutrino mass matrix via a seesaw mechanism is constructed by assuming that the underlying symmetry of both heavy Majorana and Dirac mass matrices is the discrete subgroup $\Delta(27)$ symmetry of SU(3). Using the experimental data of neutrino oscillation, the neutrino mass matrix exhibits maximal $\nu_{\mu}-\nu_{\tau}$ mixing and has a specific prediction on the effective neutrino mass in neutrinoless double beta decay which can be tested in future experiment. | Neutrino Masses via a Seesaw with Heavy Majorana and Dirac Neutrino Mass Matrices from Discrete Subgroup $\Delta (27)$ of SU(3) |
The transition away from carbon-based energy sources poses several challenges for the operation of electricity distribution systems. Increasing shares of distributed energy resources (e.g. renewable energy generators, electric vehicles) and internet-connected sensing and control devices (e.g. smart heating and cooling) require new tools to support accurate, datadriven decision making. Modelling the effect of such growing complexity in the electrical grid is possible in principle using state-of-the-art power-power flow models. In practice, the detailed information needed for these physical simulations may be unknown or prohibitively expensive to obtain. Hence, datadriven approaches to power systems modelling, including feedforward neural networks and auto-encoders, have been studied to leverage the increasing availability of sensor data, but have seen limited practical adoption due to lack of transparency and inefficiencies on large-scale problems. Our work addresses this gap by proposing a data- and knowledge-driven probabilistic graphical model for energy systems based on the framework of graph neural networks (GNNs). The model can explicitly factor in domain knowledge, in the form of grid topology or physics constraints, thus resulting in sparser architectures and much smaller parameters dimensionality when compared with traditional machine-learning models with similar accuracy. Results obtained from a real-world smart-grid demonstration project show how the GNN was used to inform grid congestion predictions and market bidding services for a distribution system operator participating in an energy flexibility market. | Knowledge- and Data-driven Services for Energy Systems using Graph Neural Networks |
The quality of acoustic echo cancellers (AECs) in real-time communication systems is typically evaluated using objective metrics like ERLE and PESQ, and less commonly with lab-based subjective tests like ITU-T Rec. P.831. We will show that these objective measures are not well correlated to subjective measures. We then introduce an open-source crowdsourcing approach for subjective evaluation of echo impairment which can be used to evaluate the performance of AECs. We provide a study that shows this tool is accurate and highly reproducible. This new tool has been recently used in the ICASSP 2021 AEC Challenge which made the challenge possible to do quickly and cost effectively. | Crowdsourcing approach for subjective evaluation of echo impairment |
The task of finding the smallest energy needed to bring a solid to its onset of mechanical instability arises in many problems in materials science, from the determination of the elasticity limit to the consistent assignment of free energies to mechanically unstable phases. However, unless the space of possible deformations is low-dimensional and a priori known, this problem is numerically difficult, as it involves minimizing a function under a constraint on its Hessian, which is computionally prohibitive to obtain in low symmetry systems, especially if electronic structure calculations are used. We propose a method that is inspired by the well-known dimer method for saddle point searches but that adds the necessary ingredients to solve for the lowest onset of mechanical instability. The method consists of two nested optimization problems. The inner one involves a dimer-like construction to find the direction of smallest curvature as well as the gradient of this curvature function. The outer optimization then minimizes energy using the result of the inner optimization problem to constrain the search to the hypersurface enclosing all points of zero minimum curvature. Example applications to both model systems and electronic structure calculations are given. | An epicycle method for elasticity limit calculations |
Open-domain conversational search (ODCS) aims to provide valuable, up-to-date information, while maintaining natural conversations to help users refine and ultimately answer information needs. However, creating an effective and robust ODCS agent is challenging. In this paper, we present a fully functional ODCS system, Ericson, which includes state-of-the-art question answering and information retrieval components, as well as intent inference and dialogue management models for proactive question refinement and recommendations. Our system was stress-tested in the Amazon Alexa Prize, by engaging in live conversations with thousands of Alexa users, thus providing empirical basis for the analysis of the ODCS system in real settings. Our interaction data analysis revealed that accurate intent classification, encouraging user engagement, and careful proactive recommendations contribute most to the users satisfaction. Our study further identifies limitations of the existing search techniques, and can serve as a building block for the next generation of ODCS agents. | Ericson: An Interactive Open-Domain Conversational Search Agent |
This commentary aims to expose the fallacy of claiming that a plasmonic silver film superlens is capable to image real subwavelength objects. This lens was proposed by the Berkeley's group who, in their misleading experiment, inappropriately regarded subwavelength apertures as the objects to be imaged whereas the main function of these apertures was to transform free space laser light into an evanescent field necessary for exciting the surface plasmon resonance phenomenon in silver. In addition, the apertures also determined the constrained effective area on the silver film where the phenomenon could occur. We provide a fresh insightful physical explanation of how this phenomenon is excited and what it entails. We emphasize the phenomenon's important effect of subwavelength conversion (reduction) of the generated surface plasmons and their associated bound enhanced evanescent fields. | The Chimaerical Quest for the Optical Plasmonic Superlens |
Investigations of living organisms have led biologists and physicians to introduce fundamental concepts, including Brownian motion, the First Law of Thermodynamics, Poiseuille's Law of fluid flow, and Fick's Law of diffusion into physics. Given the prominence of viscous forces within and around cells and the experience of identifying and quantifying such resistive forces, biophysical cell biologists have an unique perspective in discovering the viscous forces that cause moving particles to respond to an applied force in a nonlinear manner. Using my experience as a biophysical cell biologist, I show that in any space consisting of a photon gas with a temperature above absolute zero, Doppler-shifted photons exert a velocity-dependent viscous force on moving charged particles. This viscous force prevents charged particles from exceeding the speed of light. Consequently, light itself prevents charged particles from moving faster than the speed of light. This interpretation provides a testable alternative to the interpretation provided by the Special Theory of Relativity, which contends that particles are prevented from exceeding the speed of light as a result of the relativity of time. | Charged Particles are Prevented from Going Faster than the Speed of Light by Light Itself: A Biophysical Cell Biologist's Contribution to Physics |
We measure luminosity functions in the cores of four spiral-rich, poor clusters of galaxies at median redshift $z = 0.016$. In the red magnitude range -14 < M_R < -10, our data imply that the luminosity functions phi(L) \propto L^{alpha} are steep, -1.8 < alpha < -1.6, in the central 200-300 kpc of Abell 262 and of the NGC 507 Group. Abell 194 also shows signs of a steep luminosity function, alpha < -1.6, in this magnitude range. In Pegasus, the dwarf galaxy density is too low to let us constrain alpha. The NGC 507 Group and Abell 194 have been interpreted as clusters that are forming today, based on morphology and velocity structure. The high spiral galaxy fraction in Abell 262 relative to clusters like Virgo and Coma also suggests that it is young. We therefore suggest that steep luminosity functions in the range -14 < M_R < -10 may be a universal feature of young clusters and possibly of the field. If this is true, then the observed paucity of gas-rich galaxies in such environments suggests that we are finding galaxies similar to the low-surface-brightness, dark-matter-dominated dwarf spheroidal galaxies seen locally and in Virgo. This interpration is also consistent with the distribution of colors and sizes of the faint galaxies in Abell 262. If we are indeed detecting dwarf spheroidal galaxies and if they are as numerous relative to bright galaxies in the field as they are in the young clusters observed here, then the contribution of their halos to the cosmological mass density is Omega_{dSph halo} \approx 0.01. This is much smaller than values of Omega derived from dynamical measurements. | The luminosity function of dwarf galaxies in four spiral-rich groups |
The G-normal distribution was introduced by Peng [2007] as the limiting distribution in the central limit theorem for sublinear expectation spaces. Equivalently, it can be interpreted as the solution to a stochastic control problem where we have a sequence of random variables, whose variances can be chosen based on all past information. In this note we study the tail behavior of the G-normal distribution through analyzing a nonlinear heat equation. Asymptotic results are provided so that the tail "probabilities" can be easily evaluated with high accuracy. This study also has a significant impact on the hypothesis testing theory for heteroscedastic data; we show that even if the data are generated under the null hypothesis, it is possible to cheat and attain statistical significance by sequentially manipulating the error variances of the observations. | A hypothesis-testing perspective on the G-normal distribution theory |
Infrared (IR) spectroscopy is an indispensable tool for many practical applications including material analysis and sensing. Existing IR spectroscopy techniques face challenges related to the inferior performance and the high cost of IR-grade components. Here, we develop a new method, which allows studying properties of materials in the IR range using only visible light optics and detectors. It is based on the nonlinear interference of entangled photons, generated via Spontaneous Parametric Down Conversion (SPDC). In our interferometer, the phase of the signal photon in the visible range depends on the phase of an entangled IR photon. When the IR photon is traveling through the media, its properties can be found from observations of the visible photon. We directly acquire the SPDC signal with a visible range CCD camera and use a numerical algorithm to infer the absorption coefficient and the refraction index of the sample in the IR range. Our method does not require the use of a spectrometer and a slit, thus it allows achieving higher signal-to-noise ratio than the earlier developed method. | Nonlinear infrared spectroscopy free from spectral selection |
We provide the first examples of words in the free group of rank 2 which are not proper powers and for which the corresponding word maps are non-surjective on an infinite family of finite non-abelian simple groups. | Some word maps that are non-surjective on infinitely many finite simple groups |
We reconstruct the expansion history of the Universe using type Ia supernovae (SN Ia) in a manner independent of any cosmological model assumptions. To do so, we implement a non-parametric iterative smoothing method on the Joint Light-curve Analysis (JLA) data while exploring the SN Ia light-curve hyper-parameter space by Monte Carlo Markov Chain sampling. We test to see how the posteriors of these hyper-parameters depend on cosmology, whether using different dark energy models or reconstructions shift these posteriors. Our constraints on the SN Ia light-curve hyper-parameters from our model-independent analysis are very consistent with the constraints from using different parametrizations of the equation of state of dark energy, namely the flat $\Lambda\mathrm{CDM}$ cosmology, the Chevallier-Polarski-Linder (CPL) model, and the Phenomenologically Emergent Dark Energy (PEDE) model. This implies that the distance moduli constructed from the JLA data are mostly independent of the cosmological models. We also studied that the possibility the light-curve parameters evolve with redshift and our results show consistency with no evolution. The reconstructed expansion history of the Universe and dark energy properties also seem to be in good agreement with the expectations of the standard $\Lambda\mathrm{CDM}$ model. However, our results also indicate that the data still allow for considerable flexibility in the expansion history of the Universe. | Model-independent constraints on Type Ia supernova light-curve hyper-parameters and reconstructions of the expansion history of the Universe |
We introduce a variant of the classical PAC multi-armed bandit problem. There is an ordered set of $n$ arms $A[1],\dots,A[n]$, each with some stochastic reward drawn from some unknown bounded distribution. The goal is to identify the $skyline$ of the set $A$, consisting of all arms $A[i]$ such that $A[i]$ has larger expected reward than all lower-numbered arms $A[1],\dots,A[i-1]$. We define a natural notion of an $\varepsilon$-approximate skyline and prove matching upper and lower bounds for identifying an $\varepsilon$-skyline. Specifically, we show that in order to identify an $\varepsilon$-skyline from among $n$ arms with probability $1-\delta$, $$ \Theta\bigg(\frac{n}{\varepsilon^2} \cdot \min\bigg\{ \log\bigg(\frac{1}{\varepsilon \delta}\bigg), \log\bigg(\frac{n}{\delta}\bigg) \bigg\} \bigg) $$ samples are necessary and sufficient. When $\varepsilon \gg 1/n$, our results improve over the naive algorithm, which draws enough samples to approximate the expected reward of every arm; the algorithm of (Auer et al., AISTATS'16) for Pareto-optimal arm identification is likewise superseded. Our results show that the sample complexity of the skyline problem lies strictly in between that of best arm identification (Even-Dar et al., COLT'02) and that of approximating the expected reward of every arm. | Skyline Identification in Multi-Armed Bandits |
A method to perform bosonization of a fermionic theory in (1+1) dimensions in a path integral framework is developed. The method relies exclusively on the path integral property of allowing variable shifts, and does not depend on the explicit form of Greens functions. Two examples, the Schwinger model and the massless Thirring model, are worked out. | Two-Dimensional Bosonization from Variable Shifts in the Path Integral |
We demonstrate experimentally a new type of Bound state In the Continuum (BIC) which is induced by the vertical symmetry breaking of a photonic crystal slab. Such BIC emerges from the hybridization between Bloch resonances of opposite parities once the vertical symmetry is broken, and is observed in the vicinity of the anticrossing point at the lower hybrid band of the energy-momentum diagram. All experimental results are nicely reproduced by numerical simulations, and in good agreement with an analytical model based on Friedrich-Wintgen framework. Together with the possibility of dispersion engineering by vertical symmetry breaking, our results open the way to tailor photonic states in the entire complex plane to study non-hermitian photonics. | Realization of Bound state In the Continuum induced by vertical symmetry breaking in photonic lattice |
A study of heavy flavor production in different collision systems in various kinematic regions presents an opportunity to probe cold nuclear medium and hot dense matter effects. Results from the PHENIX experiment on $J/\psi$ and open charm production in Au+Au and Cu+Cu collisions at $\sqrt{s_{NN}}$ =200 GeV are presented. The data show strong $J/\psi$ suppression in central AA collisions, similar to NA50 results, and strong suppression in high $p_T$ open charm production. The $J/\psi$ production in Au+Au and d+Au collisions is compared to understand the cold nuclear medium effects. The data show significant cold nuclear effects in charm production in d+Au collisions at forward and backward rapidity ranges. | Heavy Flavor Production at PHENIX at RHIC |
A motivated q-extension of the values of the Riemann zeta function at positive integers is presented. Several irrationality and transcendence results as well as new general problems for these q-zeta values are stated. | Diophantine problems for q-zeta values |
The informatization practice of countries all over the world has shown that the level of a government's informatization is one main factor that can affect its international competitive power. At present, e-government construction is regarded as one of the most important tasks for the national economy and society upliftment and informatization in Saudi Arabia. Unlike the traditional governments, an e-government takes on a new look with its framework and operation mode more suitable for the contemporary era. In fact, it is a basic national strategy to promote Saudi Arabia's informatization by means of e-government construction. This talk firstly introduces the basic concepts and relevant viewpoints of egovernment, then reviews the development process of e-government in Saudi Arabia, and describes the current states, development strategies of e-government in Saudi Arabia. And also review e-government maturity models and synthesize them e-government maturity models are investigated, in which the authors have proposed the Delloite's six-stage model, Layne and Lee four-stage model and Accenture five-stage model. So, the main e-government maturity stages are: online presence, interaction, transaction, transformation and digital democracy. After that, according to many references, the main technologies which are used in each stage are summarized. | Electronic-government in Saudi Arabia: A positive revolution in the peninsula |
This paper studies multiclass loss systems with two layers of servers, where each server at the first layer is dedicated to a certain customer class, while the servers at the second layer can handle all customer classes. The routing of customers follows an overflow scheme, where arriving customers are preferentially directed to the first layer. Stochastic comparison and coupling techniques are developed for studying how the system is affected by packing of customers, altered service rates, and altered server configurations. This analysis leads to easily computable upper and lower bounds for the performance of the system. | Stochastic bounds for two-layer loss systems |
With the aim of characterizing rejuvenation processes in early-type galaxies, we analyzed five barred S0 galaxies showing prominent outer ring in ultraviolet (UV) imaging. We analyzed GALEX far- (FUV) and near- (NUV) UV and optical data using stellar population models and estimated the age and the stellar mass of the entire galaxies and of the UV-bright ring structures. Outer rings consist of young (<200 Myr old) stellar populations, accounting for up to 70% of the FUV flux but containing only a few % of the total stellar mass. Integrated photometry of the whole galaxies places four of these objects on the green valley, indicating a globally evolving nature. We suggest such galaxy evolution is likely driven by bar induced instabilities, i.e. inner secular evolution, that conveys gas to the nucleus and to the outer rings. At the same time, HI observations of NGC 1533 and NGC 2962 suggest external gas re-fueling can play a role in the rejuvenation processes of such galaxies. | Tracing rejuvenation events in nearby S0 galaxies |
We consider the problem of orienting the edges of the $n$-dimensional hypercube so only two different in-degrees $a$ and $b$ occur. We show that this can be done, for two specified in-degrees, if and only if an obvious necessary condition holds. Namely, there exist non-negative integers $s$ and $t$ so that $s+t=2^n$ and $as+bt=n2^{n-1}$. This is connected to a question arising from constructing a strategy for a "hat puzzle." | Hypercube orientations with only two in-degrees |
The two most commonly used models for passively modelocked lasers with fast saturable absorbers are the Haus modelocking equation (HME) and the cubic-quintic modelocking equation (CQME). The HME corresponds to a special limit of the CQME in which only a cubic nonlinearity in the fast saturable absorber is kept in the model. Here, we use singular perturbation theory to demonstrate that the CQME has a stable high-energy solution for an arbitrarily small but non-zero quintic contribution to the fast saturable absorber. As a consequence, we find that the CQME predicts the existence of stable modelocked pulses when the cubic nonlinearity is orders of magnitude larger than the value at which the HME predicts that modelocked pulses become unstable. This intrinsically larger stability range is consistent with experiments. Our results suggest a possible path to obtain high-energy and ultrashort pulses by fine tuning the higher-order nonlinear terms in the fast saturable absorber. | Nonlinear Stabilization of High-Energy and Ultrashort Pulses in Passively Modelocked Lasers with Fast Saturable Absorption |
In this paper, the mean value formula depends on the Bessel generalized shift operator corresponding to the solutions of the boundary value problem related to the Bessel operator are studied. In addition to, Riesz Bessel transforms related to the Bessel operators are studied. Since Bessel generalized shift operator is translation operator corresponding to the Bessel operator, we construct a family of RBxj by using Bessel generalized shift operator. Finally, we analysis weighted inequalities involving Riesz Bessel transforms . | High Order Riesz Transforms and Mean Value Formula for Generalized Translate Operator |
Charge ordering of V4+ and V5+ in NaV2O5 has been studied by an X-ray diffraction technique using anomalous scattering near a vanadium K-absorption edge to critically enhance a contrast between the two ions. A dramatic energy dependence of the superlattice intensities is observed below Tc=35 K. Consequently, the charge ordering pattern is the zigzag-type ladders with the unit cell 2a*2b*4c, but not the chain-type originally proposed for the spin-Peierls state. Charge disproportionation suggested in our model as the average valence V^{4.5+-delta_c/2} is observed below T_C, showing continuous variation of delta_c as a function of temperature. | X-ray Anomalous Scattering Study of a Charge-Ordered State in NaV2O5 |
Field physics was founded by Faraday introducing magnetic fields (1831), electric fields (1837) and light as an EM wave (1846), initiating the process where nature is made by matter and fields. Consider that, ordinary space is full of fields. The Faraday view is basis for modern quantum field theory. The concept of fields set up a physicality in development. Physics would like to know how far matter is created by fields. Generate matter from nonlinear fields. Faraday lines of force relating physical entities as electric charge and mass depending on fields. Our purpose is on Faraday lines for nonlinear abelian electromagnetism. Introduce the Four Bosons EM. The phenomenology of a generic charge $\{+,0,-\}$ transmitted by four bosons $\{A_{\mu}, U_{\mu}, V_{\mu}^{\pm}\}$. Nonlinear equations constituted. New Faraday lines were introduced. The potentials fields of physics are developed. Granular and collective fields strengths expressed. Four types of fields charges are derived. They are electric charge, modulated, neutral, Bianchi. This work introduces a systematic procedure of associative physics. Mass and charge are generated due to the four fields interrelationships. Masses are derived without spontaneous symmetry breaking. It is obtained naturally from gauge symmetry, London, and mixing terms. Electric charge is written by fields through the Noether theorem. EM interactions not necessarily coupled with electric charge are proposed. An enlargement of EM energy is derived. | New Faraday lines through Four Bosons EM |
In this work we obtain new lower and upper optimal bounds of general Sombor indices. Specifically, we have inequalities for these indices relating them with other indices: the first Zagreb index, the forgotten index and the first variable Zagreb index. Finally, we solve some extremal problems for general Sombor indices. | Optimal inequalities and extremal problems on the general Sombor index |
We revisit a simple dynamical model of rupture in random media with long-range elasticity to test whether rupture can be seen as a first-order or a critical transition. We find a clear scaling of the macroscopic modulus as a function of time-to-rupture and of the amplitude of the disorder, which allows us to collapse neatly the numerical simulations over more than five decades in time and more than one decade in disorder amplitude onto a single master curve. We thus conclude that, at least in this model, dynamical rupture in systems with long-range elasticity is a genuine critical phenomenon occurring as soon as the disorder is non-vanishing. | Scaling with respect to disorder in time-to-failure |
We study fractal dimension properties of singular Jacobi operators. We prove quantitative lower spectral/quantum dynamical bounds for general operators with strong repetition properties and controlled singularities. For analytic quasiperiodic Jacobi operators in the positive Lyapunov exponent regime, we obtain a sharp arithmetic criterion of full spectral dimensionality. The applications include the extended Harper's model where we obtain arithmetic results on spectral dimensions and quantum dynamical exponents. | Spectral Dimension for $\beta$-almost periodic singular Jacobi operators and the extended Harper's model |
This article is concerned with the rigidity properties of geometric realizations of incidence geometries of rank two as points and lines in the Euclidean plane; we care about the distance being preserved among collinear points. We discuss the rigidity properties of geometric realizations of incidence geometries in relation to the rigidity of geometric realizations of other well-known structures, such as graphs and hypergraphs.The $2$-plane matroid is also discussed. Further, we extend a result of Whiteley to determine necessary conditions for an incidence geometry of points and lines with exactly three points on each line, or 3-uniform hypergraphs, to have a minimally rigid realization as points and lines in the plane. We also give examples to show that these conditions are not sufficient. Finally, we examine the rigidity properties of $v_k$-configurations. We provide several examples of rigid $v_3$-configurations, and families of flexible geometric $v_3$-configurations. The exposition of the material is supported by many figures. | Exploring the infinitesimal rigidity of planar configurations of points and rods |
New global attractivity criteria are obtained for the second order difference equation \[ x_{n+1}=cx_{n}+f(x_{n}-x_{n-1}),\quad n=1, 2, ... \] via a Lyapunov-like method. Some of these results are sharp and support recent related conjectures. Also, a necessary and sufficient condition for the oscillation of this equation is obtained using comparison with a second order linear difference equation with positive coefficients. | On the global attractivity and oscillations in a class of second order difference equations from macroeconomics |
The classical approach to visualizing a flow, in terms of its streamlines, motivates a topological/soft-analytic argument for constrained variational equations. In its full generality, that argument provides an explicit formula for completely integrable solutions to a broad class of n-dimensional quasilinear exterior systems. In particular, it yields explicit solutions for extremal surfaces in Minkowski space and for Born--Infeld models. | Constructing completely integrable fields by a generalized-streamlines method |
Accurate estimate of neutrino energy loss rates are needed for the study of the late stages of the stellar evolution, in particular for cooling of neutron stars and white dwarfs. The energy spectra of neutrinos and antineutrinos arriving at the Earth can also provide useful information on the primary neutrino fluxes as well as neutrino mixing scenario (it is to be noted that these supernova neutrinos are emitted after the supernova explosion which is a much later stage of stellar evolution than that considered in this paper). Recently an improved microscopic calculation of weak-interaction mediated rates for iron isotopes was introduced using the proton-neutron quasiparticle random phase approximation (pn-QRPA) theory. Here I present for the first time the fine-grid calculation of the neutrino and anti-neutrino energy loss rates due to $^{54,55,56}$Fe in stellar matter. In the core of massive stars isotopes of iron, $^{54,55,56}$Fe, are considered to be key players in decreasing the electron-to-baryon ratio ($Y_{e}$) mainly via electron capture on these nuclide. Core-collapse simulators may find this calculation suitable for interpolation purposes and for necessary incorporation in the stellar evolution codes. The calculated cooling rates are also compared with previous calculations. | Neutrino and anti-neutrino energy loss rates due to iron isotopes suitable for core-collapse simulations |
The paper presents a tool for the mapping of the performance of building systems on European scale for different (future) time periods. The tool is to use for users and be applicable for different building systems. Users should also be able to use a broad range of climate parameters to assess the influence of climate change on these climatic parameters. Also should the calculation time be reasonable short. The mapping tool is developed in MATLAB, which can be used by other users for their own studies. | The development of a mapping tool for the evaluation of building systems for future climate scenarios on European scale |
Within simulations of molecules deposited on a surface we show that neuroevolutionary learning can design particles and time-dependent protocols to promote self-assembly, without input from physical concepts such as thermal equilibrium or mechanical stability and without prior knowledge of candidate or competing structures. The learning algorithm is capable of both directed and exploratory design: it can assemble a material with a user-defined property, or search for novelty in the space of specified order parameters. In the latter mode it explores the space of what can be made rather than the space of structures that are low in energy but not necessarily kinetically accessible. | Neuroevolutionary learning of particles and protocols for self-assembly |
In this paper, the generic part of the gauge theory of gravity is derived, based merely on the action principle and on the general principle of relativity. We apply the canonical transformation framework to formulate geometrodynamics as a gauge theory. The starting point of our paper is constituted by the general De~Donder-Weyl Hamiltonian of a system of scalar and vector fields, which is supposed to be form-invariant under (global) Lorentz transformations. Following the reasoning of gauge theories, the corresponding locally form-invariant system is worked out by means of canonical transformations. The canonical transformation approach ensures by construction that the form of the action functional is maintained. We thus encounter amended Hamiltonian systems which are form-invariant under arbitrary spacetime transformations. This amended system complies with the general principle of relativity and describes both, the dynamics of the given physical system's fields and their coupling to those quantities which describe the dynamics of the spacetime geometry. In this way, it is unambiguously determined how spin-0 and spin-1 fields couple to the dynamics of spacetime. A term that describes the dynamics of the free gauge fields must finally be added to the amended Hamiltonian, as common to all gauge theories, to allow for a dynamic spacetime geometry. The choice of this "dynamics Hamiltonian" is outside of the scope of gauge theory as presented in this paper. It accounts for the remaining indefiniteness of any gauge theory of gravity and must be chosen "by hand" on the basis of physical reasoning. The final Hamiltonian of the gauge theory of gravity is shown to be at least quadratic in the conjugate momenta of the gauge fields -- this is beyond the Einstein-Hilbert theory of General Relativity. | Canonical Transformation Path to Gauge Theories of Gravity |
This paper concerns the compact group extension \[ f:\mathbb{T}^2\to \mathbb{T}^2,\quad f (x,s)= (E(x), s+\tau(x)\ \text{mod }1) \] of an expanding map $E:\mathbb{S}^1\to \mathbb{S}^1$. The dynamics of $f$ and its stochastic perturbations have previously been studied under the so-called partial captivity condition. Here we prove a supplementary result that shows that partial captivity is a $\mathscr{C}^r$ generic condition on $\tau$, once we fix $E$. | The partial captivity condition for U(1) extensions of expanding maps on the circle |
Equivariant networks have been adopted in many 3-D learning areas. Here we identify a fundamental limitation of these networks: their ambiguity to symmetries. Equivariant networks cannot complete symmetry-dependent tasks like segmenting a left-right symmetric object into its left and right sides. We tackle this problem by adding components that resolve symmetry ambiguities while preserving rotational equivariance. We present OAVNN: Orientation Aware Vector Neuron Network, an extension of the Vector Neuron Network. OAVNN is a rotation equivariant network that is robust to planar symmetric inputs. Our network consists of three key components. 1) We introduce an algorithm to calculate symmetry detecting features. 2) We create a symmetry-sensitive orientation aware linear layer. 3) We construct an attention mechanism that relates directional information across points. We evaluate the network using left-right segmentation and find that the network quickly obtains accurate segmentations. We hope this work motivates investigations on the expressivity of equivariant networks on symmetric objects. | Breaking the Symmetry: Resolving Symmetry Ambiguities in Equivariant Neural Networks |
In this note we study boundedness of a large class of maximal operators in Sobolev spaces that includes the spherical maximal operator. We also study the size of the set of Lebesgue points with respect to convergence associated with such maximal operators. | Sobolev spaces, Lebesgue points and maximal functions |
Motivated from the study of eccentricity, center, and sum of eccentricities in graphs and trees, we introduce several new distance-based global and local functions based on the smallest distance from a vertex to some leaf (called the `uniformity' at that vertex). Some natural extremal problems on trees are considered. Then the middle parts of a tree is discussed and compared with the well-known center of a tree. The values of the global functions are also compared with the sum of eccentricities and some sharp bounds are established. Last but not the least, we show that the difference between the eccentricity and the uniformity, when considered as a local function, behaves in a very similar way as the eccentricity itself. | Variations of the eccentricity and their properties in trees |
In Analog-to-digital (A/D) conversion, signal decimation has been proven to greatly improve the efficiency of data storage while maintaining high accuracy. When one couples signal decimation with the $\Sigma\Delta$ quantization scheme, the reconstruction error decays exponentially with respect to the bit-rate. We build on our previous result, which extends signal decimation to finite frames, albeit only up to the second order. In this study, we introduce a new scheme called adapted decimation, which yields polynomial reconstruction error decay rate of arbitrary order with respect to the oversampling rate, and exponential with respect to the bit-rate. | Adapted Decimation on Finite Frames for Arbitrary Orders of Sigma-Delta Quantization |
Cosmological data provide a powerful tool in the search for physics beyond the Standard Model (SM). An interesting target are light relics, new degrees of freedom which decoupled from the SM while relativistic. Nearly massless relics contribute to the radiation energy budget, and are commonly parametrized as variations in the effective number $N_{\rm eff}$ of neutrino species. Additionally, relics with masses greater than $10^{-4}$ eV become non-relativistic before today, and thus behave as matter instead of radiation. This leaves an imprint in the clustering of the large-scale structure of the universe, as light relics have important streaming motions, mirroring the case of massive neutrinos. Here we forecast how well current and upcoming cosmological surveys can probe light massive relics (LiMRs). We consider minimal extensions to the SM by both fermionic and bosonic relic degrees of freedom. By combining current and upcoming cosmic-microwave-background and large-scale-structure surveys, we forecast the significance at which each LiMR, with different masses and temperatures, can be detected. We find that a very large coverage of parameter space will be attainable by upcoming experiments, opening the possibility of exploring uncharted territory for new physics beyond the SM. | Finding eV-scale Light Relics with Cosmological Observables |
Pause insertion, also known as phrase break prediction and phrasing, is an essential part of TTS systems because proper pauses with natural duration significantly enhance the rhythm and intelligibility of synthetic speech. However, conventional phrasing models ignore various speakers' different styles of inserting silent pauses, which can degrade the performance of the model trained on a multi-speaker speech corpus. To this end, we propose more powerful pause insertion frameworks based on a pre-trained language model. Our approach uses bidirectional encoder representations from transformers (BERT) pre-trained on a large-scale text corpus, injecting speaker embedding to capture various speaker characteristics. We also leverage duration-aware pause insertion for more natural multi-speaker TTS. We develop and evaluate two types of models. The first improves conventional phrasing models on the position prediction of respiratory pauses (RPs), i.e., silent pauses at word transitions without punctuation. It performs speaker-conditioned RP prediction considering contextual information and is used to demonstrate the effect of speaker information on the prediction. The second model is further designed for phoneme-based TTS models and performs duration-aware pause insertion, predicting both RPs and punctuation-indicated pauses (PIPs) that are categorized by duration. The evaluation results show that our models improve the precision and recall of pause insertion and the rhythm of synthetic speech. | Duration-aware pause insertion using pre-trained language model for multi-speaker text-to-speech |
The potential importance of short-distance nuclear effects in double-$\beta$ decay is assessed using a lattice QCD calculation of the $nn\rightarrow pp$ transition and effective field theory methods. At the unphysical quark masses used in the numerical computation, these effects, encoded in the isotensor axial polarisability, are found to be of similar magnitude to the nuclear modification of the single axial current, which phenomenologically is the quenching of the axial charge used in nuclear many-body calculations. This finding suggests that nuclear models for neutrinoful and neutrinoless double-$\beta$ decays should incorporate this previously neglected contribution if they are to provide reliable guidance for next-generation neutrinoless double-$\beta$ decay searches. The prospects of constraining the isotensor axial polarisabilities of nuclei using lattice QCD input into nuclear many-body calculations are discussed. | The isotensor axial polarisability and lattice QCD input for nuclear double-$\beta$ decay phenomenology |
A novel 3D shape classification scheme, based on collaborative representation learning, is investigated in this work. A data-driven feature-extraction procedure, taking the form of a simple projection operator, is in the core of our methodology. Provided a shape database, a graph encapsulating the structural relationships among all the available shapes, is first constructed and then employed in defining low-dimensional sparse projections. The recently introduced method of CRPs (collaborative representation based projections), which is based on L2-Graph, is the first variant that is included towards this end. A second algorithm, that particularizes the CRPs to shape descriptors that are inherently nonnegative, is also introduced as potential alternative. In both cases, the weights in the graph reflecting the database structure are calculated so as to approximate each shape as a sparse linear combination of the remaining dataset objects. By way of solving a generalized eigenanalysis problem, a linear matrix operator is designed that will act as the feature extractor. Two popular, inherently high dimensional descriptors, namely ShapeDNA and Global Point Signature (GPS), are employed in our experimentations with SHREC10, SHREC11 and SCHREC 15 datasets, where shape recognition is cast as a multi-class classification problem that is tackled by means of an SVM (support vector machine) acting within the reduced dimensional space of the crafted projections. The results are very promising and outperform state of the art methods, providing evidence about the highly discriminative nature of the introduced 3D shape representations. | 3D Shape Classification Using Collaborative Representation based Projections |
The Parkes Galactic All-Sky Survey (GASS) is a survey of Galactic atomic hydrogen (HI) emission in the Southern sky covering declinations $\delta \leq 1^{\circ}$ using the Parkes Radio Telescope. The survey covers $2\pi$ steradians with an effective angular resolution of ~16', at a velocity resolution of 1.0 km/s, and with an rms brightness temperature noise of 57 mK. GASS is the most sensitive, highest angular resolution survey of Galactic HI emission ever made in the Southern sky. In this paper we outline the survey goals, describe the observations and data analysis, and present the first-stage data release. The data product is a single cube at full resolution, not corrected for stray radiation. Spectra from the survey and other data products are publicly available online. | GASS: The Parkes Galactic All-Sky Survey. I. Survey Description, Goals, and Initial Data Release |
Intermediate/Extreme mass ratio inspiral (I/EMRI) system provides a good tool to test the nature of gravity in strong field. Based on the method of osculating orbits, we compute the orbital evolutions of I/EMRIs on quasi-elliptic orbits in both Einstein's general relativity and Brans-Dicke theory. The extra monopolar and dipolar channels in Brans-Dicke theory accelerate the orbital decay, so it is important to consider the effects of monopolar and dipolar emissions on the waveform. With the help of accurate orbital motion, we generate waveform templates which include both monopolar and dipolar contributions for I/EMRIs on eccentric orbits in Brans-Dicke theory. With a two-year observation of gravitational waves emitted from I/EMRIs by LISA, we get the most stringent constraint on the Brans-Dicke coupling parameter $\omega_0>10^6$. | Constraint on Brans-Dicke theory from intermediate/extreme mass ratio inspirals |
We show a possibility that strong ``magnetic field'' $\sim 10^{15} $G is produced by color ferromagnetic quark matter in neutron stars. In the quark matter a color magnetic field is generated spontaneously owing to Savvidy mechanism and a gluon condensate arises for the stabilization of the field. Since the quark matter is electrically charged in the neutron stars, the rotation of the quarks around the color magnetic field produces the strong ``magnetic field''. | Color Ferromagnetism of Quark Matter ; a Possible Origin of Strong Magnetic Field in Magnetars |
Advances in sensor networks enable pervasive health monitoring and patient-specific treatments that take into account the patients medical history, current state, genetic background, and personal habits. However, sensors are often battery power limited and vastly differ in their application related requirements. In this paper, we address both of these problems. Specifically, we study IEEE 802.15.6 ultra-wideband (UWB) wireless body area networks (WBANs) that use impulse radio (IR). We formulate the joint optimization of the payload size and number of pulses per symbol to optimize the energy efficiency under the minimum rate constraint. The proposed algorithm, cross-layer optimization for energy efficiency (CLOEE), enables us to carry out a cross-layer resource allocation that addresses the rate and reliability trade-off in the physical (PHY) layer as well as the packet size optimization and transmission efficiency for the medium access control (MAC) layer. Simulation results demonstrate that CLOEE can provide an order of magnitude improvement in to static strategies. | CLOEE - Cross-Layer Optimization for Energy Efficiency of IEEE 802.15.6 IR-UWB WBANs |
We investigate the evolution of galactic disks in N-body Tree-SPH simulations. We find that disks, initially truncated at three scale-lengths, can triple their radial extent, solely driven by secular evolution. Both Type I (single exponential) and Type II (down-turning) observed disk surface-brightness profiles can be explained by our findings. We relate these results to the strong angular momentum outward transfer, resulting from torques and radial migration associated with multiple patterns, such as central bars and spiral waves of different multiplicity. We show that even for stars ending up on cold orbits, the changes in angular momentum exhibit complex structure as a function of radius, unlike the expected effect of transient spirals alone. Focussing on one of our models, we find evidence for non-linear coupling among m=1, 2, 3 and 4 density waves, where m is the pattern multiplicity. We suggest that the naturally occurring larger resonance widths at galactic radii beyond four scale-lengths may have profound consequences on the formation and location of breaks in disk density profiles, provided spirals are present at such large distances. We also consider the effect of gas inflow and show that when in-plane smooth gas accretion of ~5 M_sun/yr is included, the outer disks become more unstable, leading to a strong increase in the stellar velocity dispersion. This, in turn, causes the formation of a Type III (up-turning) profile in the old stellar population. We propose that observations of Type III surface brightness profiles, combined with an up-turn in the stellar velocity dispersions beyond the disk break, could be a signature of ongoing gas-accretion. The results of this study suggest that disk outskirts comprised of stars migrated from the inner disk would have relatively large radial velocity dispersions, and significant thickness when seen edge-on. [Abridged] | Evolution of Galactic Discs: Multiple Patterns, Radial Migration and Disc Outskirts |
A relation is obtained between weak values of quantum observables and the consistency criterion for histories of quantum events. It is shown that ``strange'' weak values for projection operators (such as values less than zero) always correspond to inconsistent families of histories. It is argued that using the ABL rule to obtain probabilities for counterfactual measurements corresponding to those strange weak values gives inconsistent results. This problem is shown to be remedied by using the conditional weight, or pseudo-probability, obtained from the multiple-time application of Luders' Rule. It is argued that an assumption of reverse causality (a form of time symmetry) implies that weak values obtain, in a restricted sense, at the time of the weak measurement as well as at the time of post-selection. Finally, it is argued that weak values are more appropriately characterised as multiple-time amplitudes than expectation values, and as such can have little to say about counterfactual questions. | Weak Values and Consistent Histories in Quantum Theory |
We explore the Borel complexity of some basic families of subsets of a countable group (large, small, thin, sparse and other) defined by the size of their elements. Applying the obtained results to the Stone-\v{C}ech compactification $\beta G$ of $G$, we prove, in particular, that the closure of the minimal ideal of $\beta G$ is of type $F_{\sigma\delta}$. | The descriptive look at the size of subsets of groups |
The energy landscape approach has been useful to help understand the dynamic properties of supercooled liquids and the connection between these properties and thermodynamics. The analysis in numerical models of the inherent structure (IS) trajectories -- the set of local minima visited by the liquid -- offers the possibility of filtering out the vibrational component of the motion of the system on the potential energy surface and thereby resolving the slow structural component more efficiently. Here we report an analysis of an IS trajectory for a widely-studied water model, focusing on the changes in hydrogen bond connectivity that give rise to many IS separated by relatively small energy barriers. We find that while the system \emph{travels} through these IS, the structure of the bond network continuously modifies, exchanging linear bonds for bifurcated bonds and usually reversing the exchange to return to nearly the same initial configuration. For the 216 molecule system we investigate, the time scale of these transitions is as small as the simulation time scale ($\approx 1$ fs). Hence for water, the transitions between each of these IS is relatively small and eventual relaxation of the system occurs only by many of these transitions. We find that during IS changes, the molecules with the greatest displacements move in small ``clusters'' of 1-10 molecules with displacements of $\approx 0.02-0.2$ nm, not unlike simpler liquids. However, for water these clusters appear to be somewhat more branched than the linear ``string-like'' clusters formed in a supercooled Lennar d-Jones system found by Glotzer and her collaborators. | Transitions between Inherent Structures in Water |
Searches for extrasolar planets using the periodic Doppler shift of stellar spectral lines have recently achieved a precision of 60 cm/s (ref 1), which is sufficient to find a 5-Earth-mass planet in a Mercury-like orbit around a Sun-like star. To find a 1-Earth-mass planet in an Earthlike orbit, a precision of 5 cm/s is necessary. The combination of a laser frequency comb with a Fabry-Perot filtering cavity has been suggested as a promising approach to achieve such Doppler shift resolution via improved spectrograph wavelength calibration, with recent encouraging results. Here we report the fabrication of such a filtered laser comb with up to 40- GHz (1-A) line spacing, generated from a 1- GHz repetition-rate source, without compromising long-term stability, reproducibility or spectral resolution. This wide-line-spacing comb, or `astro-comb', is well matched to the resolving power of high-resolution astrophysical spectrographs. The astro-comb should allow a precision as high as 1 cm/s in astronomical radial velocity measurements. | A laser frequency comb that enables radial velocity measurements with a precision of 1 cm s$^{-1}$ |
We give a general decomposition of SU(N) connection and derive a generalized Skyrme-Faddeev action as the effective action of SU(N) QCD in the low energy limit. The result is obtained by separating the topological degrees which describes the non-Abelian monopoles from the dynamical degree of gauge potential, and integrating all the dynamical degrees of SU(N) QCD. | Decomposition of SU(N) connection and Effective Theory of SU(N) QCD |
We present the splashback radius measurements around the SRG/eROSITA eFEDS X-ray selected galaxy clusters by cross-correlating them with HSC S19A photometric galaxies. The X-ray selection is expected to be less affected by systematics related to projection that affects optical cluster finder algorithms. We use a nearly volume-limited sample of 109 galaxy clusters selected in 0.5-2.0 keV band having luminosity $L_X > 10^{43.5}\,{\rm erg s^{-1} h^{-2}}$ within the redshift $z<0.75$ and obtain measurements of the projected cross-correlation with a signal-to-noise of $17.43$. We model our measurements to infer a three-dimensional profile and find that the steepest slope is sharper than $-3$ and associate the location with the splashback radius. We infer the value of the 3D splashback radius $r_{\rm sp} = 1.45^{+0.30}_{-0.26}\,{\rm h^{-1} Mpc}$. We also measure the weak lensing signal of the galaxy clusters and obtain halo mass $\log[M_{\rm 200m}/{\rm h^{-1}M_\odot}] = 14.52 \pm 0.06$ using the HSC-S16A shape catalogue data at the median redshift $z=0.46$ of our cluster sample. We compare our $r_{\rm sp}$ values with the spherical overdensity boundary $r_{\rm 200m} = 1.75 \pm 0.08\,{\rm h^{-1} Mpc}$ based on the halo mass which is consistent within $1.2\sigma$ with the $\Lambda$CDM predictions. Our constraints on the splashback radius, although broad, are the best measurements thus far obtained for an X-ray selected galaxy cluster sample. | The eROSITA Final Equatorial-Depth Survey (eFEDS) -- Splashback radius of X-ray galaxy clusters using galaxies from HSC survey |
In this article we present a high-precision evaluation of the expansions in $\e=(4-d)/2$ of (up to) four-loop scalar vacuum master integrals, using the method of difference equations developed by S. Laporta. We cover the complete set of `QED-type' master integrals, i.e. those with a single mass scale only (i.e. $m_i\in\{0,m\}$) and an even number of massive lines at each vertex. Furthermore, we collect all that is known analytically about four-loop `QED-type' masters, as well as about {\em all} single-mass-scale vacuum integrals at one-, two- and three-loop order. | High-precision epsilon expansions of single-mass-scale four-loop vacuum bubbles |
We propose a trick which enables one to incorporate the Gribov horizon into the Schwinger-Dyson equation in Landau and Coulomb gauge Yang-Mills theory, using the Gribov-Zwanziger framework with the horizon term. We find a family of solutions parameterized by one-parameter $w_R(0)$ which was overlooked so far by assuming to be zero implicitly. The family includes both the scaling and decoupling solutions, and specification of the parameter discriminates between them. In the Landau gauge we discuss a possible decoupling solution satisfying the Kugo-Ojima criterion for color confinement. | Decoupling and scaling solutions in Yang-Mills theory with the Gribov horizon |
We present preliminary observational results of the multi-site STEPHI campaign on the cluster NGC 1817. The three observatories involved are San Pedro Martir (Mexico), Xing Long (China) and the Observatorio del Teide (Spain) - giving an ideal combination to maximise the duty cycle. The cluster has 12 known delta Scuti stars and at least two detached eclipsing binary systems. This combination of characteristics is ideal for extracting information about global parameters of the targets, which will in turn impose strict constraints on the stellar models. From an initial comparison with stellar models using the known fundamental parameters, and just the observed pulsation frequencies and measured effective temperatures, it appears that a lower value of initial helium mass fraction will most likely explain the observations of these stars. | Preliminary results from the STEPHI2009 campaign on the open cluster NGC 1817 |
Relying on the techniques and ideas from our recent paper [13], we prove several anti-classification results for various rigidity conditions in countable abelian and nilpotent groups. We prove three main theorems: (1) the rigid abelian groups are complete co-analytic in the space of countable torsion-free abelian groups ($\mathrm{TFAB}_\omega$); (2) the Hopfian groups are complete co-analytic in $\mathrm{TFAB}_\omega$; (3) the co-Hopfian groups are complete co-analytic in the space of countable $2$-nilpotent groups. In combination with our result from [13, S5], which shows that the endo-rigid abelian groups are complete co-analytic in $\mathrm{TFAB}_\omega$, this shows that four major notions of rigidity from (abelian) group theory are as complex as possible as co-analytic problems. Further, the second and third theorem above solve two open questions of Thomas from [18], who asked this for the space of all countable groups. We leave open the question of whether the co-Hopfian mixed abelian groups are complete co-analytic in the space of countable abelian groups, but we reduce the problem to a concrete question on profinite groups, showing that if $G$ is a countable co-Hopfian abelian reduced group, then, for every prime number $p$, the torsion subgroup $\mathrm{Tor}_p(G)$ of $G$ is finite and $G$ embeds in the profinite group $ \prod_{p \in \mathbb{P}} \mathrm{Tor}_p(G)$. | Anti-Classification Results for Rigidity Conditions in Abelian and Nilpotent Groups |
We describe the angular power spectrum of unresolved 3.6 micron IR light in Spitzer GOODS fields. The amplitude of the anisotropy spectrum decreases with decreasing flux threshold to which resolved sources are removed from images. When all pixels brighter than a Vega magnitude of 24.6 are removed, the amplitude of the power spectrum at arcminute angular scales can be described with an extra component of z>8 sources with a IRB contribution around 0.4 nW m^-2 sr-1. The shape of the power spectrum, however, is more consistent with that expected for unresolved, faint galaxies at lower redshifts with Vega magnitudes fainter than 23 with a total 3.6 micron intensity between 0.1 to 0.8 nW m^-2 sr^-1. We confirm this assumption by showing that large-scale power decreases rapidly when the unresolved clustering spectrum is measured from a processed HDF-N IRAC image where locations of faint ACS sources with no IR counterparts were also masked. Based on resolved counts and unresolved fluctuations, we find that, at most, about 7.0 nW m^-2 sr^-1 can be ascribed to galaxies. | IR Background Anisotropies in Spitzer GOODS images and constraints on first galaxies |
Several experiments and models have highlighted the importance of neuronal heterogeneity in brain dynamics and function. However, how such a cell-to-cell diversity can affect cortical computation, synchronization, and neuronal communication is still under debate. Previous studies have focused on the effect of neuronal heterogeneity in one neuronal population. Here we are specifically interested in the effect of neuronal variability on the phase relations between two populations, which can be related to different cortical communication hypotheses. It has been recently shown that two spiking neuron populations unidirectionally connected in a sender-receiver configuration can exhibit anticipated synchronization (AS), which is characterized by a negative phase-lag. This phenomenon has been reported in electrophysiological data of non-human primates and human EEG during a visual discrimination cognitive task. In experiments, the unidirectional coupling could be accessed by Granger causality and can be accompanied by both positive or negative phase difference between cortical areas. Here we propose a model of two coupled populations in which the neuronal heterogeneity can determine the dynamical relation between the sender and the receiver and can reproduce phase relations reported in experiments. Depending on the distribution of parameters characterizing the neuronal firing patterns, the system can exhibit both AS and the usual delayed synchronization regime (DS, with positive phase) as well as a zero-lag synchronization regime and phase bistability between AS and DS. Furthermore, we show that our network can present diversity in their phase relations maintaining the excitation-inhibition balance. | Neuronal heterogeneity modulates phase-synchronization between unidirectionally coupled populations with excitation-inhibition balance |
Using data from the Sloan Digital Sky Survey Moving Object Catalog, we study color as a function of size for C-complex families in the Main Asteroid Belt to improve our understanding of space weathering of carbonaceous materials. We find two distinct spectral slope trends: Hygiea-type and Themis-type. The Hygiea-type families exhibit a reduction in spectral slope with increasing object size until a minimum slope value is reached and the trend reverses with increasing slope with increasing object size. The Themis family shows an increase in spectral slope with increasing object size until a maximum slope is reached and the spectral slope begins to decrease slightly or plateaus for the largest objects. Most families studied show the Hygiea-type trend. The processes responsible for these distinct changes in spectral slope affect several different taxonomic classes within the C-complex and appear to act quickly to alter the spectral slopes of the family members. | Space Weathering within C-Complex Main Belt Asteroid Families |
The physics of Cosmic ray (CR) transport remains a key uncertainty in assessing whether CRs can produce galaxy-scale outflows consistent with observations. In this paper, we elucidate the physics of CR-driven galactic winds for CR transport dominated by diffusion. A companion paper considers CR streaming. We use analytic estimates validated by time-dependent spherically-symmetric simulations to derive expressions for the mass-loss rate, momentum flux, and speed of CR-driven galactic winds, suitable for cosmological-scale or semi-analytic models of galaxy formation. For CR diffusion coefficients $\kappa \gtrsim r_0 c_i$ where $r_0$ is the base radius of the wind and $c_i$ is the isothermal gas sound speed, the asymptotic wind energy flux is comparable to that supplied to CRs, and the outflow rapidly accelerates to supersonic speeds. By contrast, for $\kappa \lesssim r_0 c_i$, CR-driven winds accelerate more slowly and lose most of their energy to gravity, a CR analogue of photon-tired stellar winds. Given CR diffusion coefficients estimated using Fermi gamma-ray observations of pion decay, we predict mass-loss rates in CR-driven galactic winds of order the star formation rate for dwarf and disc galaxies. The dwarf galaxy mass-loss rates are small compared to the mass-loadings needed to reconcile the stellar and dark matter halo mass functions. For nuclear starbursts (e.g., M82, Arp 220), CR diffusion and pion losses suppress the CR pressure in the galaxy and the strength of CR-driven winds. We discuss the implications of our results for interpreting observations of galactic winds and for the role of CRs in galaxy formation. | The Physics of Galactic Winds Driven by Cosmic Rays I: Diffusion |
The partially attractive character of the dipole-dipole interaction leads to phonon instability in dipolar condensates, which is followed by collapse in three-dimensional geometries. We show that the nature of this instability is fundamentally different in two-dimensional condensates, due to the dipole-induced stabilization of two-dimensional bright solitons. As a consequence, a transient gas of attractive solitons is formed, and collapse may be avoided. In the presence of an harmonic confinement, the instability leads to transient pattern formation followed by the creation of stable two-dimensional solitons. This dynamics should be observable in on-going experiments, allowing for the creation of stable two-dimensional solitons for the first time ever in quantum gases. | Phonon instability in two-dimensional dipolar Bose-Einstein Condensates |
Using an approximate likelihood method adapted to band--power estimates, we analyze the ensemble of first generation cosmic microwave background anisotropy experiments to deduce constraints over a six--dimensional parameter space describing Inflation--generated adiabatic, scalar fluctuations. The basic preferences of simple Inflation scenarios are consistent with the data set: flat geometries $(\OmT \equiv 1-\Omk \sim 1)$ and a scale--invariant primeval spectrum ($n\sim 1$) are favored. Models with significant negative curvature ($\OmT < 0.7$) are eliminated, while constraints on postive curvature are less stringent. Degeneracies among the parameters prevent independent determinations of the matter density $\OmM$ and the cosmological constant $\Lambda$, and the Hubble constant $\Ho$ remains relatively unconstrained. We also find that the height of the first Doppler peak relative to the amplitude suggested by data at larger $l$ indicates a high baryon content ($\Omb h^2$), almost independently of the other parameters. Besides the overall qualitative advance expected of the next generation experiments, their improved dipole calibrations will be particularly useful for constraining the peak height. Our analysis includes a {\em Goodness--of--Fit} statistic applicable to power estimates and which indicates that the maximum likelihood model provides an acceptable fit to the data set. | Cosmological Constraints from the Cosmic Microwave Background |
Long-duration $\gamma$-ray bursts (GRBs) accompany the collapse of massive stars and carry information about the central engine. However, no 3D models have been able to follow these jets from their birth by a black-hole (BH) to the photosphere. We present the first such 3D general-relativity magnetohydrodynamic simulations, which span over 6 orders of magnitude in space and time. The collapsing stellar envelope forms an accretion disk, which drags inwardly the magnetic flux that accumulates around the BH, becomes dynamically important and launches bipolar jets. The jets reach the photosphere at $\sim10^{12}$ cm with an opening angle $\theta_j\sim6^\circ$ and a Lorentz factor $\Gamma_j\lesssim 30$, unbinding $\gtrsim90\%$ of the star. We find that (i) the disk-jet system spontaneously develops misalignment relative to the BH rotational axis. As a result, the jet wobbles with an angle $\theta_t\sim12^\circ$, which can naturally explain quiescent times in GRB lightcurves. The effective opening angle for detection $\theta_j+\theta_t$ suggests that the intrinsic GRB rate is lower by an order of magnitude than standard estimates. This suggests that successful GRBs may be rarer than currently thought and emerge in only $\sim 0.1\%$ of supernovae Ib/c, implying that jets are either not launched or choked inside most supernova Ib/c progenitors. (ii) The magnetic energy in the jet decreases due to mixing with the star, resulting in jets with a hybrid composition of magnetic and thermal components at the photosphere, where $\sim 10\%$ of the gas maintains magnetization $\sigma\gtrsim 0.1$. This indicates that both a photospheric component and reconnection may play a role in the prompt emission. | Black hole to photosphere: 3D GRMHD simulations of collapsars reveal wobbling and hybrid composition jets |
Neutron stars provide unique conditions to study cold dense nuclear matter at extreme densities. Due to these extreme conditions additional hadronic degrees of freedom are expected to be populated,including hyperons. This talk will focus on the influence of hyperons on the neutron star equation ofstate. In particular the contribution of the lambda hyperon will be discussed, as a first approximation to describing exotic neutron star equations of state. The system under consideration is where the strong nuclear force is described by the exchange of mesons and applying the relativistic mean field theory to study dense nuclear matter. As expected, the inclusion of the lambda hyperon softens the neutron star equation of state (EoS). A softer EoS will reduce the maximum mass attainable by the modeled neutron star with such EoS. While hyperons are certainly not unexpected in high density systems, but there presence seems to be contradicted by observations of high mass neutron stars. This contradiction is known as the "hyperon puzzle". The expected influx of observational data from massive new radio-telescopes like the Square Kilometer Array (SKA) will provide observations that can be supported and evolve theoretical models of nuclear matter. Therefore, the study of hyperonic matter is not only relevant to nuclear theory, but also locally to Botswana as an African partner country of the SKA. | The lambda hyperon and the hyperon puzzle |
We develop a non-intrusive data-driven modeling framework for power network dynamics using the Lift and Learn approach of \cite{QianWillcox2020}. A lifting map is applied to the snapshot data obtained from the original nonlinear swing equations describing the underlying power network such that the lifted-data corresponds to quadratic nonlinearity. The lifted data is then projected onto a lower dimensional basis and the reduced quadratic matrices are fit to this reduced lifted data using a least-squares measure. The effectiveness of the proposed approach is investigated by two power network models. | Data-driven modeling of power networks |
We consider a class of simplest Majoron models where neutrino- majoron couplings can be in the range $g \sim 10^{-5}-10^{-3}$ leading to the observability of neutrinoless double beta decay with majoron emission. The majoron is a singlet of the electroweak gauge symmetry, thus avoiding conflict with the LEP data on Z decay, which rules out the triplet and doublet majoron models. | Observable Majoron Emission in Neutrinoless Double Beta Decay |
We consider a class of $\mathcal C^{4}$ partially hyperbolic systems on $\mathbb T^2$ described by maps $F_\varepsilon(x,\theta)=(f(x,\theta),\theta+\varepsilon\omega(x,\theta))$ where $f(\cdot,\theta)$ are expanding maps of the circle. For sufficiently small $\varepsilon$ and $\omega$ generic in an open set, we precisely classify the SRB measures for $F_\varepsilon$ and their statistical properties, including exponential decay of correlation for H\"older observables with explicit and nearly optimal bounds on the decay rate. | Statistical properties of mostly contracting fast-slow partially hyperbolic systems |
New physics beyond the Standard Model is required to give mass to the light neutrinos. One of the simplest ideas is to introduce new heavy, gauge singlet fermions that play the role of right-handed neutrinos in a seesaw mechanism. They could have large Yukawa couplings to the Higgs boson, affecting the Higgs couplings and in particular the triple Higgs coupling $\lambda_{HHH}^{}$, the measure of which is one of the major goals of the LHC and of future colliders. We present a study of the impact of these heavy neutrinos on $\lambda_{HHH}^{}$ at the one-loop level, first in a simplified 3+1 model with one heavy Dirac neutrino and then in the inverse seesaw model. Taking into account all possible experimental constraints, we find that sizeable deviations of the order of 35% are possible, large enough to be detected at future colliders, making the triple Higgs coupling a new, viable observable to constrain neutrino mass models. The effects are generic and are expected in any new physics model including TeV-scale fermions with large Yukawa couplings to the Higgs boson, such as those using the neutrino portal. | Impact of heavy sterile neutrinos on the triple Higgs coupling |
In the 1st part of this work [DHdS18], we studied affine group schemes over a discrete valuation ring (DVR) by means of Neron blowups. We also showed how to apply these findings to throw light on the group schemes coming from Tannakian categories of D-modules. In the present work, we follow up this theme. We show that a certain class of affine group schemes of "infinite type", Neron blowups of formal subgroups, are quite typical. We also explain how these group schemes appear naturally in Tannakian categories of D-modules. To conclude, we isolate a Tannakian property of affine group schemes, named prudence, which allows one to verify if the underlying ring of functions is a free module over the base ring. This is then successfully applied to obtain a general result on the structure of differential Galois groups over complete DVRs. | On the structure of affine flat group schemes over discrete valuation rings, II |
We show that charge fluctuation processes are crucial for the nonlinear heat conductance through an interacting nanostructure, even far from a resonance. We illustrate this for an Anderson quantum dot accounting for the first two leading orders of the tunneling in a master equation. The often made assumption that off-resonant transport proceeds entirely by virtual occupation of charge states, underlying exchange-scattering models, can fail dramatically for heat transport. The identified energy-transport resonances in the Coulomb blockade regime provide new qualitative information about relaxation processes, for instance by strong negative differential heat conductance relative to the heat current. These can go unnoticed in the charge current, making nonlinear heat-transport spectroscopy with energy-level control a promising experimental tool. | Charge fluctuations in nonlinear heat transport |
Networking operational costs and environmental concerns have lately driven the quest for energy efficient equipment. In wired networks, energy efficient Ethernet (EEE) interfaces can greatly reduce power demands when compared to regular Ethernet interfaces. Their power saving capabilities have been studied and modeled in many research articles in the last few years, together with their effects on traffic delay. However, to this date, all articles have considered them in isolation instead of as part of a network of EEE interfaces. In this paper we develop a model for the traffic delay on a network of EEE interfaces. We prove that, whatever the network topology, the per interface delay increment due to the power savings capabilities is bounded and, in most scenarios, negligible. This confirms that EEE interfaces can be used in all but the most delay constrained scenarios to save considerable amounts of power. | Delay Properties of Energy Efficient Ethernet Networks |
We review the connection of $Y$- and $Q$-systems with the BPS spectra of $4D$ $\mathcal{N}=2$ supersymmetric QFTs. For each finite BPS chamber of a $\mathcal{N}=2$ model which is UV superconformal, one gets a periodic $Y$-system, while for each finite BPS chamber of an asymptotically-free $\mathcal{N}=2$ QFT one gets a $Q$-system i.e. a rational recursion all whose solutions satisfy a linear recursion with constant coefficients (depending on the initial conditions). For instance, the classical $ADE$ $Y$-systems of Zamolodchikov correspond to the $ADE$ Argyres-Douglas $\mathcal{N}=2$ SCFTs, while the usual $ADE$ $Q$-systems to pure $\mathcal{N}=2$ SYM. After having motivated the correspondence both from the QFT and the TBA sides, and having introduced the basic tricks of the trade, we exploit the connection to construct and SOLVE new $Y$- and $Q$-systems. In particular, we present the new $Y$-systems associated to the $E_6,E_7,E_8$ Minahan-Nemeshanski SCFTs and to the $D_2(G)$ SCFTs. We also present new $Q$-system corresponding to SYM coupled to specific matter systems such that the YM $\beta$-function remains negative. | $Y$ systems, $Q$ systems, and 4D $\mathcal{N}=2$ supersymmetric QFT |
In several matching markets, in order to achieve diversity, agents' priorities are allowed to vary across an institution's available seats, and the institution is let to choose agents in a lexicographic fashion based on a predetermined ordering of the seats, called a (capacity-constrained) lexicographic choice rule. We provide a characterization of lexicographic choice rules and a characterization of deferred acceptance mechanisms that operate based on a lexicographic choice structure under variable capacity constraints. We discuss some implications for the Boston school choice system and show that our analysis can be helpful in applications to select among plausible choice rules. | Lexicographic Choice Under Variable Capacity Constraints |
The Counterfactual package implements the estimation and inference methods of Chernozhukov, Fern\'andez-Val and Melly (2013) for counterfactual analysis. The counterfactual distributions considered are the result of changing either the marginal distribution of covariates related to the outcome variable of interest, or the conditional distribution of the outcome given the covariates. They can be applied to estimate quantile treatment effects and wage decompositions. This paper serves as an introduction to the package and displays basic functionality of the commands contained within. | Counterfactual: An R Package for Counterfactual Analysis |
In spite of its great promises for energy efficient power conversion, the electronic quality of cubic silicon carbide (3C-SiC) on silicon is currently limited by the presence of a variety of extended defects in the heteroepitaxial material. However, the specific role of the different defects on the electronic transport is still under debate. In this work, a macro- and nano-scale characterization of Schottky contacts on 3C-SiC/Si was carried out, to elucidate the impact of the anti-phase-boundaries (APBs) and stacking-faults (SFs) on the forward and reverse current-voltage characteristics of these devices. Current mapping of 3C-SiC by conductive atomic force microscopy (CAFM) directly showed the role of APBs as the main defects responsible of the reverse bias leakage, while both APBs and SFs were shown to work as preferential current paths under forward polarization. Distinct differences between these two kinds of defects were also confirmed by electronic transport simulations of a front-to-back contacted SF and APB. These experimental and simulation results provide a picture of the role played by different types of extended defects on the electrical transport in vertical or quasi-vertical devices based on 3C-SiC/Si, and can serve as a guide for improving material quality by defects engineering. | Impact of stacking faults and domain boundaries on the electronic transport in cubic silicon carbide probed by conductive atomic force microscopy |
We consider the BPS conditions of eleven dimensional supergravity, restricted to an appropriate ansatz for black holes in four non-compact directions. Assuming the internal directions to be described by a circle fibration over a K\"ahler manifold and considering the case where the complex structure moduli are frozen, we recast the resulting flow equations in terms of polyforms on this manifold. The result is a set of equations that are in direct correspondence with those of gauged supergravity models in four dimensions consistent with our simplifying assumptions. In view of this correspondence even for internal manifolds that do not correspond to known consistent truncations, we comment on the possibility of obtaining gauged supergravities from reductions on K\"ahler manifolds. | AdS4 black holes from M-theory |
In this paper we consider the cohomology of four groups related to the virtual braids of [Kauffman] and [Goussarov-Polyak-Viro], namely the pure and non-pure virtual braid groups (PvB_n and vB_n, respectively), and the pure and non-pure flat braid groups (PfB_n and fB_n, respectively). The cohomologies of PvB_n and PfB_n admit an action of the symmetric group S_n. We give a description of the cohomology modules H^i(PvB_n,Q) and H^i(PfB_n,Q) as sums of S_n-modules induced from certain one-dimensional representations of specific subgroups of S_n. This in particular allows us to conclude that H^i(PvB_n,Q) and H^i(PfB_n,Q) are uniformly representation stable, in the sense of [Church-Farb]. We also give plethystic formulas for the Frobenius characteristics of these S_n-modules. We then derive a number of constraints on which S_n irreducibles may appear in H^i(PvB_n,Q) and H^i(PfB_n,Q). In particular, we show that the multiplicity of the alternating representation in H^i(PvB_n,Q) and H^i(PfB_n,Q) is identical, and moreover is nil for sufficiently large $n$. We use this to recover the (previously known) fact that the multiplicity of the alternating representation in H^i(PB_n,Q) is nil (here PB_n is the ordinary pure braid group). We also give an explicit formula for H^i(vB_n,Q) and show that H^i(fB_n,Q)=0. Finally, we give Hilbert series for the character of the action of S_n on H^i(PvB_n,Q) and H^i(PfB_n,Q). An extension of the standard `Koszul formula' for the graded dimension of Koszul algebras to graded characters of Koszul algebras then gives Hilbert series for the graded characters of the respective quadratic dual algebras. | On the Action of the Symmetric Group on the Cohomology of Groups Related to (Virtual) Braids |
Generalizing classical results of the theory of absolutely summing operators, in this paper we characterize the duals of a quite large class of Banach operator ideals defined or characterized by the transformation of vector-valued sequences. | Duality theory for generalized summing linear operators |
We present the effective field equations obtained from a generalized gravity action with Euler-Poincare term and a cosmological constant in a $D$ dimensional bulk space-time. A class of plane-symmetric solutions that describe a 3-brane world embedded in a D=5 dimensional bulk space-time are given. | Plane Symmetric Solutions of Gravitational Field Equations in Five Dimensions |
This work deals with the inhomogeneous Landau equation on the torus in the cases of hard, maxwellian and moderately soft potentials. We first investigate the linearized equation and we prove exponential decay estimates for the associated semigroup. We then turn to the nonlinear equation and we use the linearized semigroup decay in order to construct solutions in a close-to-equilibrium setting. Finally, we prove a exponential stability for such a solution, with a rate as close as we want to the optimal rate given by the semigroup decay. | Cauchy problem and exponential stability for the inhomogeneous Landau equation |
I present numerical updates of the Standard-Model predictions for the mass and width differences and the CP asymmetries in flavor-specific decays in Bs-Bs-bar and Bd-Bd-bar mixing. Then I discuss the current status of new physics in these mixing amplitudes. | B Mixing in the Standard Model and Beyond |
One of the most important O($\alpha_s^2$) corrections to the $B \to X_s \gamma$ branching ratio originates from interference of contributions from the current-current and photonic dipole operators. Its value has been estimated using an interpolation in the charm quark mass between the known results at $m_c=0$ and for $m_c \ll m_b/2$. An explicit calculation for the physical value of $m_c$ is necessary to remove the associated uncertainty. In the present work, we evaluate all the ultraviolet counterterm contributions that are relevant for this purpose. | NNLO QCD counterterm contributions to $B$ \to $X_s \gamma$ for the physical value of $m_c$ |
We have analyzed the total HI contents of 72 Hickson compact groups of galaxies (HCGs) and the detailed spatial distributions and kinematics of HI within a subset of 16 groups using the high angular resolution observations obtained with the VLA in order to investigate a possible evolutionary scenario for these densest systems in the present day galaxy hierarchy. For the more homogeneous subsample of 48 groups, we found a mean HI deficiency of DefHI = 40 (40% of the expected HI for the LBs and morphological types of the member galaxies). The individual galaxies show larger degrees of deficiency than the groups globally, DefHI = 0.62 (24% of the expected HI), due in most cases to efficient gas stripping from individual galaxies into the group environment visible in the VLA maps. The degree of deficiency is found to be similar to the central galaxies of Virgo and Coma cluster, and Coma I group, in spite of the significantly different characteristics of these environments. Phase transformation of the HI should explain the deficiency. The detection rate of HCGs at X-ray wavelengths is larger for HI deficient groups. In the evolutionary scenario we propose, the amount of detected HI would decrease further with evolution, by continuous tidal stripping and/or heating. The H2 content also tends to be lower than expected for the galaxies in HI deficient groups, this may suggest that the HI stripping by frequent tidal interaction breaks the balance between the disruption of molecular clouds by star formation and the replenishment from the ambient HI. | Where is the Neutral Atomic Gas in Hickson Groups? |
Recurrent neural networks have proved to be an effective method for statistical language modeling. However, in practice their memory and run-time complexity are usually too large to be implemented in real-time offline mobile applications. In this paper we consider several compression techniques for recurrent neural networks including Long-Short Term Memory models. We make particular attention to the high-dimensional output problem caused by the very large vocabulary size. We focus on effective compression methods in the context of their exploitation on devices: pruning, quantization, and matrix decomposition approaches (low-rank factorization and tensor train decomposition, in particular). For each model we investigate the trade-off between its size, suitability for fast inference and perplexity. We propose a general pipeline for applying the most suitable methods to compress recurrent neural networks for language modeling. It has been shown in the experimental study with the Penn Treebank (PTB) dataset that the most efficient results in terms of speed and compression-perplexity balance are obtained by matrix decomposition techniques. | Compression of Recurrent Neural Networks for Efficient Language Modeling |
The theory of ternary semigroups, groups and algebras is reformulated in the abstract arrow language. Then using the reversing arrow ansatz we define ternary comultiplication, bialgebras and Hopf algebras and investigate their properties. The main property "to be binary derived" is considered in detail. The co-analog of Post theorem is formulated. It is shown that there exist 3 types of ternary coassociativity, 3 types of ternary counits and 2 types of ternary antipodes. Some examples are also presented. | Basic concepts of ternary Hopf algebras |
In this paper, we study the stability problem of a star-shaped network of elastic strings with a local Kelvin-Voigt damping. Under the assumption that the damping coefficients have some singularities near the transmission point, we prove that the semigroup corresponding to the system is polynomially stable and the decay rates depends on the speed of the degeneracy. This result improves the decay rate of the semigroup associated to the system on an earlier result of Z.~Liu and Q.~Zhang in \cite{LZ} involving the wave equation with local Kelvin-Voigt damping and non-smooth coefficient at interface. | Stability of a star-shaped network with local Kelvin-Voigt damping and non-smooth coefficient at interface |
The quantum nilpotent algebras U^w_-(g), defined by De Concini-Kac-Procesi and Lusztig, are large classes of iterated skew polynomial rings with rich ring theoretic structure. In this paper, we prove in an explicit way that all torus invariant prime ideals of the algebras U^w_-(g) are polynormal. In the special case of the algebras of quantum matrices, this construction yields explicit polynormal generating sets consisting of quantum minors for all of their torus invariant prime ideals. This gives a constructive proof of the Goodearl-Lenagan polynormality conjecture. Furthermore we prove that Spec U^w_-(g) is normally separated for all simple Lie algebras g and Weyl group elements w, and deduce from it that all algebras U^w_-(g) are catenary. | A proof of the Goodearl-Lenagan polynormality conjecture |
A method of computer simulation of Time-Resolved X-ray Diffraction (TRXD) in asymmetric Laue (transmission) geometry with an arbitrary propagating strain perpendicular to the crystal surface is presented. We present two case studies for possible strain generation by short-pulse laser irradiation: (i) a thermoelastic-like analytic model; (ii) a numerical model including effects of electron-hole diffusion, Auger recombination, deformation potential and thermal diffusion. A comparison with recent experimental results is also presented. | Simulations of Time-Resolved X-Ray Diffraction in Laue Geometry |
The Coronavirus pandemic has affected the normal course of life. People around the world have taken to social media to express their opinions and general emotions regarding this phenomenon that has taken over the world by storm. The social networking site, Twitter showed an unprecedented increase in tweets related to the novel Coronavirus in a very short span of time. This paper presents the global sentiment analysis of tweets related to Coronavirus and how the sentiment of people in different countries has changed over time. Furthermore, to determine the impact of Coronavirus on daily aspects of life, tweets related to Work From Home (WFH) and Online Learning were scraped and the change in sentiment over time was observed. In addition, various Machine Learning models such as Long Short Term Memory (LSTM) and Artificial Neural Networks (ANN) were implemented for sentiment classification and their accuracies were determined. Exploratory data analysis was also performed for a dataset providing information about the number of confirmed cases on a per-day basis in a few of the worst-hit countries to provide a comparison between the change in sentiment with the change in cases since the start of this pandemic till June 2020. | Global Sentiment Analysis Of COVID-19 Tweets Over Time |
Recent image inpainting methods have made great progress but often struggle to generate plausible image structures when dealing with large holes in complex images. This is partially due to the lack of effective network structures that can capture both the long-range dependency and high-level semantics of an image. We propose cascaded modulation GAN (CM-GAN), a new network design consisting of an encoder with Fourier convolution blocks that extract multi-scale feature representations from the input image with holes and a dual-stream decoder with a novel cascaded global-spatial modulation block at each scale level. In each decoder block, global modulation is first applied to perform coarse and semantic-aware structure synthesis, followed by spatial modulation to further adjust the feature map in a spatially adaptive fashion. In addition, we design an object-aware training scheme to prevent the network from hallucinating new objects inside holes, fulfilling the needs of object removal tasks in real-world scenarios. Extensive experiments are conducted to show that our method significantly outperforms existing methods in both quantitative and qualitative evaluation. Please refer to the project page: \url{https://github.com/htzheng/CM-GAN-Inpainting}. | CM-GAN: Image Inpainting with Cascaded Modulation GAN and Object-Aware Training |
We compute the entanglement entropy and Renyi entropies of arbitrary pure states in pure Jackiw-Teitelboim gravity in Lorentz signature. We apply the quantum Hubeny-Rangamani-Ryu-Takayanagi formula by computing the quantum corrected area term and the bulk entropy term. The sum of these two terms for the Hartle-Hawking state agrees with the black hole entropy above extremality computed from the Euclidean disk path integral. We interpret the area term as the universal contribution of a defect operator that plays a crucial role in our Lorentzian interpretation of the Euclidean replica trick in gravity. | Entanglement Entropy in Jackiw-Teitelboim Gravity |
In the ekpyrotic scenario the Universe is initially collapsing, the energy density coming from a scalar field with a negative exponential potential. On the basis of a calculation ignoring the gravitational back-reaction the authors of the scenario claim that during collapse the vacuum fluctuation creates a perturbation in the comoving curvature, which has a flat spectrum in accordance with observation. In this note the back-reaction is included, and it is found that the spectrum during collapse is strongly scale-dependent with negligible magnitude. The spectrum is continuous across the bounce if the spacetime is smooth, making it unlikely that the ekpyrotic scenario can be compatible with observation. | The primordial curvature perturbation in the ekpyrotic Universe |
We report the statistics of electric field fluctuations produced by SPC/E water inside a Kihara solute given as a hard-sphere core with a Lennard-Jones layer at its surface. The statistics of electric field fluctuations, obtained from numerical simulations, are studied as a function of the magnitude of a point dipole placed close to the solute-water interface. The free energy surface as a function of the electric field projected on the dipole direction shows a cross-over with the increasing dipole magnitude. While it is a single-well harmonic function at low dipole values, it becomes a double-well surface at intermediate dipole moment magnitudes, transforming to a single-well surface, with a non-zero minimum position, at still higher dipoles. A broad intermediate region where the interfacial waters fluctuate between the two minima is characterized by intense field fluctuations, with non-Gaussian statistics and the variance far exceeding the linear-response expectations. The excited state of the surface water is found to be lifted above the ground state by the energy required to break approximately two hydrogen bonds. This state is pulled down in energy by the external electric field of the solute dipole, making it readily accessible to thermal excitations. The excited state is a localized surface defect in the hydrogen-bond network creating a stress in the nearby network, but otherwise relatively localized in the region closest to the solute dipole. | Non-Gaussian statistics of electrostatic fluctuations of hydration shells |
Deep learning technologies have demonstrated remarkable effectiveness in a wide range of tasks, and deep learning holds the potential to advance a multitude of applications, including in edge computing, where deep models are deployed on edge devices to enable instant data processing and response. A key challenge is that while the application of deep models often incurs substantial memory and computational costs, edge devices typically offer only very limited storage and computational capabilities that may vary substantially across devices. These characteristics make it difficult to build deep learning solutions that unleash the potential of edge devices while complying with their constraints. A promising approach to addressing this challenge is to automate the design of effective deep learning models that are lightweight, require only a little storage, and incur only low computational overheads. This survey offers comprehensive coverage of studies of design automation techniques for deep learning models targeting edge computing. It offers an overview and comparison of key metrics that are used commonly to quantify the proficiency of models in terms of effectiveness, lightness, and computational costs. The survey then proceeds to cover three categories of the state-of-the-art of deep model design automation techniques: automated neural architecture search, automated model compression, and joint automated design and compression. Finally, the survey covers open issues and directions for future research. | Design Automation for Fast, Lightweight, and Effective Deep Learning Models: A Survey |
The approximate numerical method for a calculation of a quantum wave impedance in a case of a potential energy with a complicated spatial structure is considered. It was proved that the approximation of a real potential by a piesewise constant function is also reasonable in a case of using a quantum impedance approach.The dependence of an accuracy of numerical calculations on a number of cascads by which a real potential is represented was found. The method of including into a consideration of zero-range singular potentials was developed. | Numerical study of quantum mechanical systems using a quantum wave impedance approach |
We present a novel deep neural network architecture for end-to-end scene flow estimation that directly operates on large-scale 3D point clouds. Inspired by Bilateral Convolutional Layers (BCL), we propose novel DownBCL, UpBCL, and CorrBCL operations that restore structural information from unstructured point clouds, and fuse information from two consecutive point clouds. Operating on discrete and sparse permutohedral lattice points, our architectural design is parsimonious in computational cost. Our model can efficiently process a pair of point cloud frames at once with a maximum of 86K points per frame. Our approach achieves state-of-the-art performance on the FlyingThings3D and KITTI Scene Flow 2015 datasets. Moreover, trained on synthetic data, our approach shows great generalization ability on real-world data and on different point densities without fine-tuning. | HPLFlowNet: Hierarchical Permutohedral Lattice FlowNet for Scene Flow Estimation on Large-scale Point Clouds |
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