cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Representations of sl(2,C) in the BGG category O and master symmetries
Creators: name: Wang, Jing Ping
Publisher: name: arXiv
Year: 2014
Subjects: subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: FOS: Physical sciences

description: In this paper, we first give a short account on the indecomposable sl(2,C) modules in the Bernstein-Gelfand-Gelfand (BGG) category O. We show these modules naturally arise for homogeneous integrable nonlinear evolutionary systems. We then develop an approach to construct master symmetries for such integrable systems. This method naturally enables us to compute the hierarchy of time-dependent symmetries. We finally illustrate the method using both classical and new examples. We compare our approach to the known existing methods used to construct master symmetries. For the new integrable equations such as a Benjamin-Ono type equation, a new integrable Davey-Stewartson type equation and two different versions of (2+1)-dimensional generalised Volterra Chains, we generate their conserved densities using their master symmetries.
Dynamics of a spherical particle in an acoustic field: a multiscale approach
Creators: name: Xie, Jin-Han
name: Vanneste, Jacques
Publisher: name: arXiv
Year: 2014
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences
subject: 76Q05

description: A rigid spherical particle in an acoustic wave field oscillates at the wave period but has also a mean motion on a longer time scale. The dynamics of this mean motion is crucial for numerous applications of acoustic microfluidics, including particle manipulation and flow visualisation. It is controlled by four physical effects: acoustic (radiation) pressure, streaming, inertia and viscous drag. In this paper, we carry out a systematic multiscale analysis of the problem in order to assess the relative importance of these effects depending on the parameters of the system that include wave amplitude, wavelength, sound speed, sphere radius, and viscosity. We identify two distinguished regimes characterised by a balance among three of the four effects, and we derive the equations that govern the mean particle motion in each regime. This recovers and organises classical results by King, Gor'kov and Doinikov, clarifies the range of validity of these results, and reveals a new nonlinear dynamical regime. In this regime, the mean motion of the particle remains intimately coupled to that of the surrounding fluid, and while viscosity affects the fluid motion, it plays no part in the acoustic pressure. Simplified equations, valid when only two physical effects control the particle motion, are also derived. They are used to obtain sufficient conditions for the particle to behave as a passive tracer of the Lagrangian-mean fluid motion.
description: 31 pages, 3 figures
Multimedia report of II Intensive Creative Workshop on Future - Deliverable 2.4
Creators: name: Tola, Elisabetta
name: Troncoso, Andrea
name: Conti, Francesca
Publisher: name: Zenodo
Year: 2022

description: Deliverable 2.4 "Multimedia report of Intensive Creative Workshop II on Futurisation" explains how the second FEDORA Creative Workshop was designed, organised and performed. It will refer in some parts to Deliverable 2.3, due to their close connection. New languages and formats were part of the frame given to participants, enriched by the results from the First Creative Workshop and by presenting case studies coming from the benchmarking phase.
The workshop took place in Bologna, Italy, on the 21st and 22nd of April 2022, and gathered 9 experts from 4 European countries and 9 different knowledge and artistic fields. After 8 hours of intense work, the experts developed three prototypes that reflect the ethos of the FEDORA project and that could well be tested and tried in educational environments.
This document is the fourth deliverable of Work Package 2, "Exploring new languages, narratives and arts in science education - Analysis of Blindspot 2", led by formicablu.
Simulating the Action Principle in Optics
Creators: name: Bari, Refath
Publisher: name: arXiv
Year: 2021
Subjects: subject: Physics Education (physics.ed-ph)
subject: FOS: Physical sciences

description: Light has a fascinating property: it always travels the path that takes the least time between any two points. This is the motivating property behind optical phenomena such as Reflection and Refraction. The unreasonable economic efficiency of light is captured by a single proposition: the Principle of Least Action (PLA) in Optics. The PLA can be difficult for students to comprehend because unlike reflection and refraction, which emerge from optimizing a one-dimensional function, the PLA emerges from optimizing an infinite-dimensional functional. Furthermore, students may be confused by the formulation of the Lagrangian, or the counterintuitive paths generated by the PLA. To address these difficulties, this paper presents three simulations which demonstrate the PLA in Optics. Simulations have proven to be effective pedagogical tools in making mathematical abstractions such as the Action accessible to undergraduate students. The three simulations in this paper are as follows: light reflecting in equal angles, light refracting through different mediums, and light traveling the path of least time in an arbitrary refractive profile. We then consider the famous Brachistochrone problem as a special case of the third simulation. The interactive simulations discussed in the paper, along with supplemental discussion questions, video tutorials, and fully commented code, are available here.
description: 10 Pages
Entanglement Entropies of Non-Equilibrium Finite-Spin Systems
Creators: name: Nakagawa, Koichi
Publisher: name: arXiv
Year: 2014
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: For the purpose of clarifying a new approach to understanding quantum entanglement using thermofield dynamics (TFD), entanglement entropies of non-equilibrium finite-spin systems are examined for both traditional and extended cases. The extended entanglement entropy, $\hat{S}$, is derived, and it is found that the conditions for the maximum entangled state can be obtained through this approach. The capacity of the TFD-based method to distinguish between states in quantum systems is confirmed.
description: 7 pages, 4figures
Numerical scheme for a spatially inhomogeneous matrix-valued quantum Boltzmann equation
Creators: name: Lu, Jianfeng
name: Mendl, Christian B.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Computational Physics (physics.comp-ph)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We develop an efficient algorithm for a spatially inhomogeneous matrix-valued quantum Boltzmann equation derived from the Hubbard model. The distribution functions are $2 \times 2$ matrix-valued to accommodate the spin degree of freedom, and the scalar quantum Boltzmann equation is recovered as special case when all matrices are proportional to the identity. We use Fourier discretization and fast Fourier transform to efficiently evaluate the collision kernel with spectral accuracy, and numerically investigate periodic, Dirichlet and Maxwell boundary conditions. Model simulations quantify the convergence to local and global thermal equilibrium.
description: 9 figures
Automatic Landmarks Correspondence Detection in Medical Images with an Application to Deformable Image Registration
Creators: name: Grewal, Monika
name: Wiersma, Jan
name: Westerveld, Henrike
name: Bosman, Peter A. N.
name: Alderliesten, Tanja
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: Purpose: Deformable Image Registration (DIR) can benefit from additional guidance using corresponding landmarks in the images. However, the benefits thereof are largely understudied, especially due to the lack of automatic landmark detection methods for three-dimensional (3D) medical images. Approach: We present a Deep Convolutional Neural Network (DCNN), called DCNN-Match, that learns to predict landmark correspondences in 3D images in a self-supervised manner. We trained DCNN-Match on pairs of Computed Tomography (CT) scans containing simulated deformations. We explored five variants of DCNN-Match that use different loss functions and assessed their effect on the spatial density of predicted landmarks and the associated matching errors. We also tested DCNN-Match variants in combination with the open-source registration software Elastix to assess the impact of predicted landmarks in providing additional guidance to DIR. Results: We tested our approach on lower-abdominal CT scans from cervical cancer patients: 121 pairs containing simulated deformations and 11 pairs demonstrating clinical deformations. The results showed significant improvement in DIR performance when landmark correspondences predicted by DCNN-Match were used in the case of simulated (p = $0e^0$) as well as clinical deformations (p = 0.030). We also observed that the spatial density of the automatic landmarks with respect to the underlying deformation affect the extent of improvement in DIR. Finally, DCNN-Match was found to generalize to Magnetic Resonance Imaging (MRI) scans without requiring retraining, indicating easy applicability to other datasets. Conclusions: DCNN-Match learns to predict landmark correspondences in 3D medical images in a self-supervised manner, which can improve DIR performance.
description: accepted paper in the Journal of Medical Imaging
All-optical noise spectroscopy of a solid-state spin
Creators: name: Farfurnik, Demitry
name: Singh, Harjot
name: Luo, Zhouchen
name: Bracker, Allan S.
name: Carter, Samuel G.
name: Pettit, Robert M.
name: Waks, Edo
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Noise spectroscopy elucidates the fundamental noise sources in spin systems, thereby serving as an essential tool toward developing spin qubits with long coherence times for quantum information processing, communication, and sensing. But existing techniques for noise spectroscopy that rely on microwave fields become infeasible when the microwave power is too weak to generate Rabi rotations of the spin. Here, we demonstrate an alternative all-optical approach to performing noise spectroscopy. Our approach utilizes coherent Raman rotations of the spin state with controlled timing and phase to implement Carr-Purcell-Meiboom-Gill pulse sequences. Analyzing the spin dynamics under these sequences enables us to extract the noise spectrum of a dense ensemble of nuclear spins interacting with a single spin in a quantum dot, which has thus far only been modeled theoretically. By providing spectral bandwidths of over 100 MHz, our approach enables the studies of spin dynamics and decoherence for a broad range of solid-state spin qubits.
Generalized linking-type theorem with applications to strongly indefinite problems with sign-changing nonlinearities
Creators: name: Bernini, Federico
name: Bieganowski, Bartosz
Publisher: name: arXiv
Year: 2021
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics
subject: 35Q55, 35A15, 35J20, 35Q60, 58E05, 78A25

description: We show the linking-type result which allows us to study strongly indefinite problems with sign-changing nonlinearities. We apply the abstract theory to the singular Schrödinger equation $$ -Δu + V(x)u + \frac{a}{r^2} u = f(u) - λg(u), \quad x = (y,z) \in \mathbb{R}^K \times \mathbb{R}^{N-K}, \ r = |y|, $$ where $$ 0 \not\in σ\left( -Δ+ \frac{a}{r^2} + V(x) \right). $$ As a consequence we obtain also the existence of solutions to the nonlinear curl-curl problem.
The Big Constant Out, The Small Constant In
Creators: name: Gabadadze, Gregory
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Some time ago, Tseytlin has made an original and unusual proposal for an action that eliminates an arbitrary cosmological constant. The form of the proposed action, however, is strongly modified by gravity loop effects, ruining its benefit. Here I discuss an embedding of Tseytlin's action into a broader context, that enables to control the loop effects. The broader context is another universe, with its own metric and dynamics, but only globally connected to ours. One possible Lagrangian for the other universe is that of unbroken AdS supergravity. A vacuum energy in our universe does not produce any curvature for us, but instead increases or decreases the AdS curvature in the other universe. I comment on how to introduce the accelerated expansion in this framework in a technically natural way, and consider the case where this is done by the self-accelerated solutions of massive gravity and its extensions.
description: 14 pages; a brief paragraph unfolded; 3 refs added; minor improvements
Drift-Diffusion Dynamics and Phase Separation in Curved Cell Membranes and Dendritic Spines: Hybrid Discrete-Continuum Methods
Creators: name: Tran, Patrick D.
name: Blanpied, Thomas A.
name: Atzberger, Paul J.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Biological Physics (physics.bio-ph)
subject: Numerical Analysis (math.NA)
subject: Pattern Formation and Solitons (nlin.PS)
subject: Subcellular Processes (q-bio.SC)
subject: Computation (stat.CO)
subject: FOS: Physical sciences
subject: FOS: Mathematics
subject: FOS: Biological sciences
subject: FOS: Computer and information sciences

description: We develop methods for investigating protein drift-diffusion dynamics in heterogeneous cell membranes and the roles played by geometry, diffusion, chemical kinetics, and phase separation. Our hybrid stochastic numerical methods combine discrete particle descriptions with continuum-level models for tracking the individual protein drift-diffusion dynamics when coupled to continuum fields. We show how our approaches can be used to investigate phenomena motivated by protein kinetics within dendritic spines. The spine geometry is hypothesized to play an important biological role regulating synaptic strength, protein kinetics, and self-assembly of clusters. We perform simulation studies for model spine geometries varying the neck size to investigate how phase-separation and protein organization is influenced by different shapes. We also show how our methods can be used to study the roles of geometry in reaction-diffusion systems including Turing instabilities. Our methods provide general approaches for investigating protein kinetics and drift-diffusion dynamics within curved membrane structures.
Guidelines for RPOs, RFOs, HEIs and high schools on "Promoting futurized science education as key dimension of RRI" - Deliverable 5.6
Creators: name: Pucetaite, Raminta
Publisher: name: Zenodo
Year: 2023
Subjects: RPOs, RFOs, HEI, futures, science, education

description: The deliverable outlines the guidelines for RPOs, RFOs, HEIs and high schools on "Promoting futurized science education as a key dimension of RRI". It builds on the recommendations produced by WP1-5, interviews and discussions with RRI experts.
The guidelines connect the AIRR principles of RRI and reflect on the MoRRI indicator SLSE1 and SDG4 targets 4.7, 4.3 and 4.4. The guidelines suggest that promoting science education as the key pillar of RRI, some changes must be initiated by RFOs as institutional changes usually follow funding decisions. Therefore, based on research evidence from the FEDORA outputs in WP1-5, RFOs are expected to promote interdisciplinarity by revising HEIs/RPOs funding principles, engaging in stakeholder dialogue to increasing the relevance of funded research to real-life problems and promoting futures studies in some national contexts. Consequently, RPOs could develop human resource management practices which favour interdisciplinary research and create "third spaces" which enable sense-making and strange-making practices. Finally, HEIs, as science education providers, should integrate futures thinking as a 21st-century skill into curricula, balance creative thinking and systems, critical thinking skills as learning outcomes, and rely on class activities and methods which speak the language of contemporary youth.
A simple model for multiple-choice collective decision making
Creators: name: Lee, Ching Hua
name: Lucas, Andrew
Publisher: name: arXiv
Year: 2014
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We describe a simple model of heterogeneous, interacting agents making decisions between $n\ge 2$ discrete choices. For a special class of interactions, our model is the mean field description of random-field Potts-like models, and is effectively solved by finding the extrema of the average energy $E$ per agent. In these cases, by studying the propagation of decision changes via avalanches, we argue that macroscopic dynamics is well-captured by a gradient flow along $E$. We focus on the permutation-symmetric case, where all $n$ choices are (on average) the same, and spontaneous symmetry breaking (SSB) arises purely from cooperative social interactions. As examples, we show that bimodal heterogeneity naturally provides a mechanism for the spontaneous formation of hierarchies between decisions, and that SSB is a preferred instability to discontinuous phase transitions between two symmetric points. Beyond the mean field limit, exponentially many stable equilibria emerge when we place this model on a graph of finite mean degree. We conclude with speculation on decision making with persistent collective oscillations. Throughout the paper, we emphasize analogies between methods of solution to our model and common intuition from diverse areas of physics, including statistical physics and electromagnetism.
description: 1+18 pages (main text) + 12 pages (appendices/references). 8 + 3 figures. v2: more references, a couple more comments/explanations and a short new section on finite size effects added
Curvaton with Nonminimal Derivative Coupling to Gravity II: Full Perturbation Analysis
Creators: name: Feng, Kaixi
name: Qiu, Taotao
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: In our previous work \cite{Feng:2013pba}, we have shown a curvaton model where the curvaton has a nonminimal derivative coupling to gravity. Such a coupling could bring us scale-invariance of the perturbations for wide range constant values of the equation-of-state of the cosmic background at the early time. In this paper, we continue our study by fully analyzing its perturbations up to the third order. Apart from the usual 2-point correlation function that has already been calculated in \cite{Feng:2013pba}, we have also taken into account the 3-point correlation functions including pure scalar part, pure tensor part, as well as the cross-correlations between scalar and tensor perturbation modes. We find that for pure scalar part, the 3-point correlation functions can generate non-Gaussianities that fits the PLANCK data very well. For pure tensor and mixed parts, the shape functions have peaks at squeezed and equilateral limits respectively, responsible for sizable $f_{NL}^{sqz}$ and $f_{NL}^{eql}$, which could be tested by the future observatioanl data.
description: Published in Phys.Rev. D90 (2014) 123508
A Comptonized Fireball Bubble: Physical Origin of Magnetar Giant Flares
Creators: name: Zhang, Zhao Joseph
name: Zhang, Bin-Bin
name: Meng, Yan-Zhi
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Magnetar giant flares (MGFs) have been long proposed to contribute at least a sub-sample of the observed short gamma-ray bursts (GRBs). The recent discovery of the short GRB 200415A in the nearby galaxy NGC 253 established a textbook-version connection between these two phenomena. Unlike previous observations of the Galactic MGFs, the unsaturated instrument spectra of GRB 200415A provide for the first time an opportunity to test the theoretical models with the observed $γ$-ray photons. This paper proposed a new readily fit-able model for the MGFs, which invokes an expanding fireball Comptonized by the relativistic magnetar wind at photosphere radius. In this model, a large amount of energy is released from the magnetar crust due to the magnetic reconnection or the starquakes of the star surface and is injected into confined field lines, forming a trapped fireball bubble. After breaking through the shackles and expanding to the photospheric radius, the thermal photons of the fireball are eventually Comptonized by the relativistic $e^{\pm}$ pairs in the magnetar wind region, which produces additional higher-energy gamma-ray emission. The model predicts a modified thermal-like spectrum characterized by a low-energy component in the Rayleigh-Jeans regime, a smooth component affected by coherent Compton scattering (CC) in the intermediate energy range, and a high-energy tail due to the inverse Compton process. By performing a Monte-Carlo fit to the observational spectra of GRB 200415A, we found that the observation of the burst is entirely consistent with our model predictions.
description: 22 pages, 9 figures, 1 table
Imaging the collective excitations of an ultracold gas using statistical correlations
Creators: name: Dubessy, Romain
name: De Rossi, Camilla
name: Badr, Thomas
name: Longchambon, Laurent
name: Perrin, Hélène
Publisher: name: arXiv
Year: 2014
Subjects: subject: Quantum Physics (quant-ph)
subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: Advanced data analysis techniques have proved to be crucial for extracting information from noisy images. Here we show that principal component analysis can be successfully applied to ultracold gases to unveil their collective excitations. By analyzing the correlations in a series of images we are able to identify the collective modes which are excited, determine their population, image their eigenfunction, and measure their frequency. Our method allows to discriminate the relevant modes from other noise components and is robust with respect to the data sampling procedure. It can be extended to other dynamical systems including cavity polariton quantum gases or trapped ions.
description: See also the supplementary material and the video abstract
Elimination of a Second-Law-attack, and all cable-resistance-based attacks, in the Kirchhoff-law-Johnson-noise (KLJN) secure key exchange system
Creators: name: Kish, Laszlo B.
name: Granqvist, Claes-Goran
Publisher: name: arXiv
Year: 2014
Subjects: subject: Emerging Technologies (cs.ET)
subject: FOS: Computer and information sciences

description: We introduce the so far most efficient attack against the Kirchhoff-law-Johnson-noise (KLJN) secure key exchange system. This attack utilizes the lack of exact thermal equilibrium in practical applications and is based on cable resistance losses and the fact that the Second Law of Thermodynamics cannot provide full security when such losses are present. The new attack does not challenge the unconditional security of the KLJN scheme, but it puts more stringent demands on the security/privacy enhancing protocol than for any earlier attack. In this paper we present a simple defense protocol to fully eliminate this new attack by increasing the noise-temperature at the side of the smaller resistance value over the noise-temperature at the at the side with the greater resistance. It is shown that this simple protocol totally removes Eve's information not only for the new attack but also for the old Bergou-Scheuer-Yariv attack. The presently most efficient attacks against the KLJN scheme are thereby completely nullified.
description: accepted for publication in Entropy (open access)
Incarnations of Skyrmions
Creators: name: Gudnason, Sven Bjarke
name: Nitta, Muneto
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Skyrmions can be transformed into lumps or baby-Skyrmions by being trapped inside a domain wall. Here we find that they can also be transformed into sine-Gordon kinks when confined by vortices, resulting in confined Skyrmions. We show this both by an effective field theory approach and by direct numerical calculations. The existence of these trapped and confined Skyrmions does not rely on higher-derivative terms when the host solitons are flat or straight. We also construct a Skyrmion as a twisted vortex ring in a model with a sixth-order derivative term.
description: RevTeX: 27 pages, 8 figures; V2: reference added
Theory of Coherent Van der Waals Matter
Creators: name: Kulic, Igor M.
name: Kulic, Miodrag L.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We explain in depth the previously proposed theory of the coherent Van der Waals(cVdW) interaction - the counterpart of Van der Waals (VdW) force - emerging in spatially coherently fluctuating electromagnetic fields. We show that cVdW driven matter is dominated by many body interactions, which are significantly stronger than those found in standard Van der Waals (VdW) systems. Remarkably, the leading 2- and 3-body interactions are of the same order with respect to the distance $(\propto R^{-6})$, in contrast to the usually weak VdW 3-body effects ($\propto R^{-9}$). From a microscopic theory we show that the anisotropic cVdW many body interactions drive the formation of low-dimensional structures such as chains, membranes and vesicles with very unusual, non-local properties. In particular, cVdW chains display a logarithmically growing stiffness with the chain length, while cVdW membranes have a bending modulus growing linearly with their size. We argue that the cVdW anisotropic many body forces cause local cohesion but also a negative effective "surface tension". We conclude by deriving the equation of state for cVdW materials and propose new experiments to test the theory, in particular the unusual 3-body nature of cVdW.
description: 26 pages, 11 figures
The 1965 Penrose singularity theorem
Creators: name: Senovilla, José M. M.
name: Garfinkle, David
Publisher: name: arXiv
Year: 2014
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: History and Philosophy of Physics (physics.hist-ph)
subject: FOS: Physical sciences

description: We review the first modern singularity theorem, published by Penrose in 1965. This is the first genuine post-Einstenian result in General Relativity, where the fundamental and fruitful concept of closed trapped surface was introduced. We include historical remarks, an appraisal of the theorem's impact, and relevant current and future work that belongs to its legacy.
description: 52 pages, 1 figure, 2 tables. Submitted to Classical and Quantum Gravity for its "Milestones of General Relativity" focus issue to be published during the Centenary Year of GR. Minor typos and references corrected. Version to be published
Quantum capacitive coupling between large-angle twisted graphene layers
Creators: name: Mrenca-Kolasinska, Alina
name: Rickhaus, Peter
name: Zheng, Giulia
name: Richter, Klaus
name: Ihn, Thomas
name: Ensslin, Klaus
name: Liu, Ming-Hao
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Large-angle twisted bilayer graphene (tBLG) is known to be electronically decoupled due to the spatial separation of the Dirac cones corresponding to individual graphene layers in the reciprocal space. The close spacing between the layers causes strong capacitive coupling, opening possibilities for applications in atomically thin devices. Here, we present a self-consistent quantum capacitance model for the electrostatics of decoupled graphene layers, and further generalize it to deal with decoupled tBLG at finite magnetic field and large-angle twisted double bilayer graphene at zero magnetic field. We probe the capacitive coupling through the conductance, showing good agreement between simulations and experiments for all the systems considered. We also propose a new experiment utilizing the decoupling effect to induce a huge and tunable bandgap in bilayer graphene by applying a moderately low bias. Our model can be extended to systems composed of decoupled graphene multilayers as well as non-graphene systems, opening a new realm of quantum-capacitively coupled materials.
description: 28 pages, 18 figures
Rational points on algebraic curves in infinite towers of number fields
Creators: name: Ray, Anwesh
Publisher: name: arXiv
Year: 2021
Subjects: subject: Number Theory (math.NT)
subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics
subject: 11G30, 11G10, 11R23 (primary), 14H40 (secondary)

description: We study a natural question in the Iwasawa theory of algebraic curves of genus $>1$. Fix a prime number $p$. Let $X$ be a smooth, projective, geometrically irreducible curve defined over a number field $K$ of genus $g>1$, such that the Jacobian of $X$ has good ordinary reduction at the primes above $p$. Fix an odd prime $p$ and for any integer $n>1$, let $K_n^{(p)}$ denote the degree-$p^n$ extension of $K$ contained in $K(μ_{p^{\infty}})$. We prove explicit results for the growth of $\#X(K_n^{(p)})$ as $n\rightarrow \infty$. When the Jacobian of $X$ has rank zero and the associated adelic Galois representation has big image, we prove an explicit condition under which $X(K_{n}^{(p)})=X(K)$ for all $n$. This condition is illustrated through examples. We also prove a generalization of Imai's theorem that applies to abelian varieties over arbitrary pro-$p$ extensions.
description: 14 pages, final version, accepted for publication in the Ramanujan Journal
Stressed Cooper pairing in QCD at high isospin density: effective Lagrangian and random matrix theory
Creators: name: Kanazawa, Takuya
name: Wettig, Tilo
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Lattice (hep-lat)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We generalize QCD at asymptotically large isospin chemical potential to an arbitrary even number of flavors. We also allow for small quark chemical potentials, which stress the coincident Fermi surfaces of the paired quarks and lead to a sign problem in Monte Carlo simulations. We derive the corresponding low-energy effective theory in both $p$- and $ε$-expansion and quantify the severity of the sign problem. We construct the random matrix theory describing our physical situation and show that it can be mapped to a known random matrix theory at low baryon density so that new insights can be gained without additional calculations. In particular, we explain the Silver Blaze phenomenon at high isospin density. We also introduce stressed singular values of the Dirac operator and relate them to the pionic condensate. Finally we comment on extensions of our work to two-color QCD.
description: 32 pages, 4 figures. v2: title change and text improvements, the version to appear in JHEP
Polycyclic Aromatic Hydrocarbons with armchair edges and the 12.7 μm band
Creators: name: Candian, A.
name: Sarre, P. J.
name: Tielens, A. G. G. M.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: In this Letter we report the results of density functional theory calculations on medium-sized neutral Polycyclic Aromatic Hydrocarbon (PAH) molecules with armchair edges. These PAH molecules possess strong C-H stretching and bending modes around 3 μm and in the fingerprint region (10-15 μm), and also strong ring deformation modes around 12.7 μm. Perusal of the entries in the NASA Ames PAHs Database shows that ring deformation modes of PAHs are common - although generally weak. We then propose that armchair PAHs with NC >65 are responsible for the 12.7 μm Aromatic Infrared Band in HII regions and discuss astrophysical implications in the context of the PAH life-cycle.
description: Minor editing
Impact of radial migration on stellar and gas radial metallicity distribution
Creators: name: Grand, Robert J. J.
name: Kawata, Daisuke
name: Cropper, Mark
Publisher: name: arXiv
Year: 2014
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Radial migration is defined as the change in guiding centre radius of stars and gas caused by gains or losses of angular momentum that result from gravitational interaction with non-axisymmetric structure. This has been shown to have significant impact on the metallicity distribution in galactic discs, and therefore affects the interpretation of Galactic archeology. We use a simulation of a Milky Way-sized galaxy to examine the effect of radial migration on the star and gas radial metallicity distribution. We find that both the star and gas component show significant radial migration. The stellar radial metallicity gradient remains almost unchanged but the radial metallicity distribution of the stars is broadened to produce a greater dispersion at all radii. However, the metallicity dispersion of the gas remains narrow. We find that the main drivers of the gas metallicity distribution evolution are metal enrichment and mixing: more efficient metal enrichment in the inner region maintains a negative slope in the radial metallicity distribution, and the metal mixing ensures the tight relationship of the gas metallicity with the radius. The metallicity distribution function reproduces the trend in the age-metallicity relation found from observations for stars younger than 1.0 Gyr in the Milky Way.
description: 11 pages, 12 figures. Matches version accepted by MNRAS. Comments welcome
Nuclear Matter from Effective Quark-Quark Interaction
Creators: name: Baldo, M.
name: Fukukawa, K.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We study neutron matter and symmetric nuclear matter with the quark-meson model for the two-nucleon interaction. The Bethe-Bruckner-Goldstone many-body theory is used to describe the correlations up to the three hole-line approximation with no extra parameters. At variance with other non-relativistic realistic interactions, the three hole-line contribution turns out to be non-negligible and to have a substantial saturation effect. The saturation point of nuclear matter, the compressibility, the symmetry energy and its slope are within the phenomenological constraints. Since the interaction also reproduces fairly well the properties of the three nucleon system, these results indicate that the explicit introduction of the quark degrees of freedom within the considered constituent quark model is expected to reduce the role of three-body forces.
description: 4 pages, 4 figures, 2 tables, matches the journal version
Token Pooling in Vision Transformers
Creators: name: Marin, Dmitrii
name: Chang, Jen-Hao Rick
name: Ranjan, Anurag
name: Prabhu, Anish
name: Rastegari, Mohammad
name: Tuzel, Oncel
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Despite the recent success in many applications, the high computational requirements of vision transformers limit their use in resource-constrained settings. While many existing methods improve the quadratic complexity of attention, in most vision transformers, self-attention is not the major computation bottleneck, e.g., more than 80% of the computation is spent on fully-connected layers. To improve the computational complexity of all layers, we propose a novel token downsampling method, called Token Pooling, efficiently exploiting redundancies in the images and intermediate token representations. We show that, under mild assumptions, softmax-attention acts as a high-dimensional low-pass (smoothing) filter. Thus, its output contains redundancy that can be pruned to achieve a better trade-off between the computational cost and accuracy. Our new technique accurately approximates a set of tokens by minimizing the reconstruction error caused by downsampling. We solve this optimization problem via cost-efficient clustering. We rigorously analyze and compare to prior downsampling methods. Our experiments show that Token Pooling significantly improves the cost-accuracy trade-off over the state-of-the-art downsampling. Token Pooling is a simple and effective operator that can benefit many architectures. Applied to DeiT, it achieves the same ImageNet top-1 accuracy using 42% fewer computations.
Implicit gradients based conservative numerical scheme for compressible flows
Creators: name: Chamarthi, Amareshwara Sainadh
name: Hoffmann, Natan
name: Nishikawa, Hiroaki
name: Frankel, Steven H.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics

description: This paper introduces a novel approach to compute the numerical fluxes at the cell boundaries for a cell-centered conservative numerical scheme. Explicit gradients used in deriving the reconstruction polynomials are replaced by high-order gradients computed by compact finite differences, referred to as implicit gradients in this paper. A problem-independent shock capturing approach via Boundary Variation Diminishing (BVD) algorithm is used to suppress oscillations for the simulation of flows with shocks and material interfaces. Several numerical test cases are carried out to verify the proposed method's capability using the implicit gradient method for compressible flows.
description: arXiv admin note: substantial text overlap with arXiv:2106.01738
The exponential map is chaotic: An invitation to transcendental dynamics
Creators: name: Shen, Zhaiming
name: Rempe-Gillen, Lasse
Publisher: name: arXiv
Year: 2014
Subjects: subject: Dynamical Systems (math.DS)
subject: Complex Variables (math.CV)
subject: FOS: Mathematics
subject: 37F10, 30D05

description: We present an elementary and conceptual proof that the complex exponential map is "chaotic" when considered as a dynamical system on the complex plane. (This result was conjectured by Fatou in 1926 and first proved by Misiurewicz 55 years later.) The only background required is a first undergraduate course in complex analysis.
description: 22 pages, 4 figures. (Provisionally) accepted for publication the American Mathematical Monthly. V2: Final pre-publication version. The article has been revised, corrected and shortened by 14 pages; see Version 1 for a more detailed discussion of further properties of the exponential map and wider transcendental dynamics
Learned Robust PCA: A Scalable Deep Unfolding Approach for High-Dimensional Outlier Detection
Creators: name: Cai, HanQin
name: Liu, Jialin
name: Yin, Wotao
Publisher: name: arXiv
Year: 2021
Subjects: subject: Machine Learning (cs.LG)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Information Theory (cs.IT)
subject: Numerical Analysis (math.NA)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics

description: Robust principal component analysis (RPCA) is a critical tool in modern machine learning, which detects outliers in the task of low-rank matrix reconstruction. In this paper, we propose a scalable and learnable non-convex approach for high-dimensional RPCA problems, which we call Learned Robust PCA (LRPCA). LRPCA is highly efficient, and its free parameters can be effectively learned to optimize via deep unfolding. Moreover, we extend deep unfolding from finite iterations to infinite iterations via a novel feedforward-recurrent-mixed neural network model. We establish the recovery guarantee of LRPCA under mild assumptions for RPCA. Numerical experiments show that LRPCA outperforms the state-of-the-art RPCA algorithms, such as ScaledGD and AltProj, on both synthetic datasets and real-world applications.
description: NeurIPS 2021
title: Η επίδραση των τεχνικών marketing στην αυτοπεποίθηση των καταναλωτών
title: The effect of marketing techniques on the confidence of consumers
titleType: AlternativeTitle
Creators: name: Παγκράτη, Άννα
Publisher: name: Πανεπιστήμιο Δυτικής Αττικής
Year: 2023
Subjects: Αυτοπεποίθηση
Αυτοβελτίωση
Τεχνικές marketing
Μάρκετινγκ
Ψυχολογικές θεωρίες
Αγοραστική συμπεριφορά
Αγορά

description: Στη σύγχρονη εποχή, με την ανάπτυξη της τεχνολογίας, των μέσων επικοινωνίας & την άμεση διακίνηση των ιδεών, ένας τομέας που έχει επίσης ανθίσει είναι αυτός της προσωπικής ανάπτυξης και αυτοβελτίωσης. Καθημερινά, ερχόμαστε σε επαφή με άρθρα, διαφημίσεις, ψυχαγωγικά μέσα, ακόμα και άτομα επιρροής, τα οποία προβάλλουν την αγάπη του εαυτού & παρακινούν το κοινό να υιοθετήσει αυτήν την αντίληψη. Φυσικά, μία τέτοια νοοτροπία, η οποία πηγάζει από – καθώς και επηρεάζει – τον εσωτερικό κόσμο του καθενός, είναι λογικό να γίνεται έναυσμα και για το κομμάτι της προσέγγισης των καταναλωτών από επιχειρήσεις & οργανισμούς, δεδομένης της σημασίας της προσωπικότητας και της αντίληψης στην αγοραστική συμπεριφορά. Στοχεύοντας στην μεταφορά του θετικού αυτού μηνύματος της αυτοεκτίμησης & αυτοπεποίθησης στους καταναλωτές ορισμένες φορές, και στην διακριτική προσπάθεια πειθούς ότι κανείς χρειάζεται κάποιο προϊόν/υπηρεσία για να γίνει καλύτερος κάποιες άλλες φορές, οι τεχνικές marketing των εταιριών μπορούν αναμφίβολα να επηρεάσουν το κοινό τους με άλλοτε θετικό & άλλοτε αρνητικό πρόσημο. Αυτός είναι και ο σκοπός αυτής της εργασίας, να εξετασθεί το ενδεχόμενο και ο βαθμός στον οποίο ένα ανθρώπινο ον μεταβάλλεται ψυχικά από τις τεχνικές αυτές, αλλά και πώς οι ίδιες οι επιχειρήσεις μπορούν να αξιοποιήσουν αυτό το κίνημα με θεμιτό τρόπο, ώστε να συμβάλλουν σε αυτό, ενδυναμώνοντας ταυτόχρονα και τη θέση τους στην αγορά. Μέσα στις επόμενες σελίδες, θα μελετηθούν και θα παρατεθούν έρευνες, θεωρητικές προσεγγίσεις, καθώς και παραδείγματα, ώστε να εξαχθούν συμπεράσματα σχετικά με το θέμα και τις ποικίλες παραμέτρους του.
Radiative decay of keV-mass sterile neutrinos in a strongly magnetized plasma
Creators: name: Dobrynina, Alexandra A.
name: Mikheev, Nicolay V.
name: Raffelt, Georg G.
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The radiative decay of sterile neutrinos with typical masses of 10 keV is investigated in the presence of a strong magnetic field and degenerate plasma. Full account is taken of the strongly modified photon dispersion relation relative to vacuum. The limiting cases of relativistic and non-relativistic plasma are analyzed. The decay rate in a strongly magnetized plasma as a function of the electron number density is compared with the un-magnetized case. We find that a strong magnetic field suppresses the catalyzing influence of the plasma on the decay rate.
description: 9 pages, 4 figures. Presentation streamlined, results unchanged. Corresponds to version published in PRD
ERQA: Edge-Restoration Quality Assessment for Video Super-Resolution
Creators: name: Kirillova, Anastasia
name: Lyapustin, Eugene
name: Antsiferova, Anastasia
name: Vatolin, Dmitry
Publisher: name: arXiv
Year: 2021
Subjects: subject: Image and Video Processing (eess.IV)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Computer and information sciences

description: Despite the growing popularity of video super-resolution (VSR), there is still no good way to assess the quality of the restored details in upscaled frames. Some SR methods may produce the wrong digit or an entirely different face. Whether a method's results are trustworthy depends on how well it restores truthful details. Image super-resolution can use natural distributions to produce a high-resolution image that is only somewhat similar to the real one. VSR enables exploration of additional information in neighboring frames to restore details from the original scene. The ERQA metric, which we propose in this paper, aims to estimate a model's ability to restore real details using VSR. On the assumption that edges are significant for detail and character recognition, we chose edge fidelity as the foundation for this metric. Experimental validation of our work is based on the MSU Video Super-Resolution Benchmark, which includes the most difficult patterns for detail restoration and verifies the fidelity of details from the original frame. Code for the proposed metric is publicly available at https://github.com/msu-video-group/ERQA.
description: Accepted for presentation at the International Conference on Computer Vision Theory and Applications (VISAPP) 2022
Products of reflections in smooth Bruhat intervals
Creators: name: Gaetz, Christian
name: Goel, Ram K.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics

description: A permutation is called smooth if the corresponding Schubert variety is smooth. Gilboa and Lapid prove that in the symmetric group, multiplying the reflections below a smooth element $w$ in Bruhat order in a compatible order yields back the element $w$. We strengthen this result by showing that such a product in fact determines a saturated chain $e \to w$ in Bruhat order, and that this property characterizes smooth elements.
description: 9 pages
title: Decoupling Between the Atmosphere and the Underlying Surface During Stable Stratification
Creators: name: Foken, Thomas
Publisher: name: University of Bayreuth
Year: 2022
Subjects: subject: Decoupling
subject: Richardson number
subject: Stable stratification
subject: Surface layer
subject: Turbulent Prandtl number
subject: 550

description: Strong temperature gradients with stable stratification immediately above the surface are typical for radiation cooling, but near-surface temperature inversions (hereinafter referred to as inversions) have hardly been studied. Both phenomena are examined in more detail by means of measurements in the Caspian Sea and Antarctica and compared with measurements made by other authors. For this purpose, tests for decoupling are applied in the first case. In the second case, the inversions can be explained in the context of counter-gradient fluxes and turbulent Prandtl numbers greater than one.