cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Analog Computing for Molecular Dynamics
Creators: name: Köppel, Sven
name: Krause, Alexandra
name: Ulmann, Bernd
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computational Physics (physics.comp-ph)
subject: Emerging Technologies (cs.ET)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences
subject: J.2; J.3; G.1.7
subject: 82M37

description: Modern analog computers are ideally suited to solving large systems of ordinary differential equations at high speed with low energy consumtion and limited accuracy. In this article, we survey N-body physics, applied to a simple water model inspired by force fields which are popular in molecular dynamics. We demonstrate a setup which simulate a single water molecule in time. To the best of our knowledge such a simulation has never been done on analog computers before. Important implementation aspects of the model, such as scaling, data range and circuit design, are highlighted. We also analyze the performance and compare the solution with a numerical approach.
description: 9 pages, 9 figures, submitted to Emerging Topics in Computing, IEEE Trans
Total $π^+ p$ cross section extracted from the leading neutron spectra at the LHC
Creators: name: Khoze, V. A.
name: Martin, A. D.
name: Ryskin, M. G.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We use the very forward neutron energy spectra measured by the Large Hadron Collider forward (LHCf) experiment at 7 TeV to extract the $π^+ p$ total cross section at centre-of-mass energies in the range 2.3$-$3.5 TeV. To do this we have to first isolate the $π$-exchange pole in forward neutron production in $pp$ collisions, by evaluating other possible contributions. Namely, those from $ρ$ and $a_2$ exchange, from both eikonal and enhanced screening effects, from migration, from neutron production by $Δ$-isobar decay and from diffractive nucleon excitations. We discuss the possible theoretical uncertainties due to the fact that the data do not exactly reach the $π$ pole. We choose the kinematical domain where the pion contribution dominates and demonstrate the role of the different corrections which could affect the final result.
description: 21 pages, 6 figures, text improved, version to be published in Phys. Rev. D
Robust MIMO Beamforming for Cellular and Radar Coexistence
Creators: name: Liu, Fan
name: Masouros, Christos
name: Li, Ang
name: Ratnarajah, Tharmalingam
Publisher: name: arXiv
Year: 2016
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: In this letter, we consider the coexistence and spectrum sharing between downlink multi-user multiple-input-multiple-output (MU-MIMO) communication and a MIMO radar. For a given performance requirement of the downlink communication system, we design the transmit beamforming such that the detection probability of the radar is maximized. While the original optimization problem is non-convex, we exploit the monotonically increasing relationship of the detection probability with the non-centrality parameter of the resulting probability distribution to obtain a convex lower-bound optimization. The proposed beamformer is designed to be robust to imperfect channel state information (CSI). Simulation results verify that the proposed approach facilitates the coexistence between radar and communication links, and illustrates a scalable trade-off between the two systems' performance.
description: 4 pages, 3 figures, accepted by IEEE Wireless Communications Letters
Two-sample goodness-of-fit tests on the flat torus based on Wasserstein distance and their relevance to structural biology
Creators: name: González-Delgado, Javier
name: González-Sanz, Alberto
name: Cortés, Juan
name: Neuvial, Pierre
Publisher: name: arXiv
Year: 2021
Subjects: subject: Methodology (stat.ME)
subject: FOS: Computer and information sciences

description: This work is motivated by the study of local protein structure, which is defined by two variable dihedral angles that take values from probability distributions on the flat torus. Our goal is to provide the space $\mathcal{P}(\mathbb{R}^2/\mathbb{Z}^2)$ with a metric that quantifies local structural modifications due to changes in the protein sequence, and to define associated two-sample goodness-of-fit testing approaches. Due to its adaptability to the space geometry, we focus on the Wasserstein distance as a metric between distributions. We extend existing results of the theory of Optimal Transport to the $d$-dimensional flat torus $\mathbb{T}^d=\mathbb{R}^d/\mathbb{Z}^d$, in particular a Central Limit Theorem. Moreover, we propose different approaches for two-sample goodness-of-fit testing for the one and two-dimensional case, based on the Wasserstein distance. We prove their validity and consistency. We provide an implementation of these tests in \textsf{R}. Their performance is assessed by numerical experiments on synthetic data and illustrated by an application to protein structure data.
Collinear order and chirality-reorientation transition in the Cairo pentagonal magnet Bi$_4$Fe$_5$O$_{13}$F
Creators: name: Tsirlin, Alexander A.
name: Rousochatzakis, Ioannis
name: Filimonov, Dmitry
name: Batuk, Dmitry
name: Frontzek, Matthias
name: Abakumov, Artem M.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We show that interlayer spins play a dual role in the Cairo pentagonal magnet Bi$_4$Fe$_5$O$_{13}$F, on one hand mediating the three-dimensional (3D) magnetic order and on the other driving spin-reorientation transitions both within and between the planes. The corresponding sequence of magnetic orders unraveled by neutron diffraction and Mössbauer spectroscopy features two orthogonal magnetic structures described by opposite local vector chiralities, and an intermediate, partly disordered phase with nearly collinear spins. A similar collinear phase has been predicted theoretically to be stabilized by quantum fluctuations, but Bi$_4$Fe$_5$O$_{13}$F is very far from the relevant parameter regime. While the observed in-plane reorientation cannot be explained by any standard frustration mechanism, our ab initio band-structure calculations reveal strong single-ion anisotropy of the interlayer Fe$^{3+}$ spins that turns out to be instrumental in controlling the local vector chirality and the associated interlayer order.
description: published version (incl. Supplemental Material)
Microscopic theory of magnetic detwinning in iron-based superconductors with large-spin rare earths
Creators: name: Maiwald, Jannis
name: Mazin, I. I.
name: Gegenwart, Philipp
Publisher: name: arXiv
Year: 2017
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Detwinning of magnetic (nematic) domains in Fe-based superconductors has so far only been obtained through mechanical straining, which considerably perturbs the ground state of these materials. The recently discovered non-mechanical detwinning in EuFe$_{2}$As$_{2}$ by ultra-low magnetic fields offers an entirely different, non-perturbing way to achieve the same goal. However, this way seemed risky due to the lack of a microscopic understanding of the magnetically driven detwinning. Specifically, the following issues remained unexplained: (i) ultra-low value of the first detwinning field of $\sim$0.1$\,$T, two orders of magnitude below that of BaFe$_{2}$As$_{2}$, (ii) reversal of the preferential domain orientation at $\sim$1$\,$T, and restoration of the low-field orientation above 10$-$15$\,$T. In this paper, we present, using published as well as newly measured data, a full theory that quantitatively explains all the observations. The key ingredient of this theory is a biquadratic coupling between Fe and Eu spins, analogous to the Fe-Fe biquadratic coupling that drives the nematic transition in this family of materials.
description: Accepted for publication in Physical Review X
Diversity of quantum ground states and quantum phase transitions of a spin-1/2 Heisenberg octahedral chain
Creators: name: Strecka, Jozef
name: Richter, Johannes
name: Derzhko, Oleg
name: Verkholyak, Taras
name: Karlova, Katarina
Publisher: name: arXiv
Year: 2017
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: The spin-1/2 Heisenberg octahedral chain with regularly alternating monomeric and square-plaquette sites is investigated using various analytical and numerical methods: variational technique, localized-magnon approach, exact diagonalization (ED) and density-matrix renormalization group (DMRG) method. The model belongs to the class of flat-band systems and it has a rich ground-state phase diagram including phases with spontaneously broken translational symmetry. Moreover, it exhibits an anomalous low-temperature thermodynamics close to continuous or discontinuous field-driven quantum phase transitions between three quantum ferrimagnetic phases, tetramer-hexamer phase, monomer-tetramer phase, localized-magnon phase and two different spin-liquid phases. If the intra-plaquette coupling is at least twice as strong as the monomer-plaquette coupling, the variational method furnishes a rigorous proof of the monomer-tetramer ground state in a low-field region and the localized-magnon approach provides an exact evidence of a single magnon trapped at each square plaquette in a high-field region. In the rest of parameter space we have numerically studied the ground-state phase diagram and magnetization process using DMRG and ED methods. It is shown that the zero-temperature magnetization curve may involve up to four intermediate plateaus at zero, one-fifth, two-fifth and three-fifth of the saturation magnetization, while the specific heat exhibits a striking low-temperature peak in a vicinity of discontinuous quantum phase transitions.
description: 13 pages, 8 figures
Emergent Supersymmetry in Local Equilibrium Systems
Creators: name: Gao, Ping
name: Liu, Hong
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: Many physical processes we observe in nature involve variations of macroscopic quantities over spatial and temporal scales much larger than microscopic molecular collision scales and can be considered as in local thermal equilibrium. In this paper we show that any classical statistical system in local thermal equilibrium has an emergent supersymmetry at low energies. We use the framework of non-equilibrium effective field theory for quantum many-body systems defined on a closed time path contour and consider its classical limit. Unitarity of time evolution requires introducing anti-commuting degrees of freedom and BRST symmetry which survive in the classical limit. The local equilibrium is realized through a $Z_2$ dynamical KMS symmetry. We show that supersymmetry is equivalent to the combination of BRST and a specific consequence of the dynamical KMS symmetry, to which we refer as the special dynamical KMS condition. In particular, we prove a theorem stating that a system satisfying the special dynamical KMS condition is always supersymmetrizable. We discuss a number of examples explicitly, including model A for dynamical critical phenomena, a hydrodynamic theory of nonlinear diffusion, and fluctuating hydrodynamics for relativistic charged fluids.
description: 45 pages
First measurement of jet mass in Pb-Pb and p-Pb collisions at the LHC
Creators: name: ALICE Collaboration
Publisher: name: arXiv
Year: 2017
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: This letter presents the first measurement of jet mass in Pb-Pb and p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV and 5.02 TeV, respectively. Both the jet energy and the jet mass are expected to be sensitive to jet quenching in the hot Quantum Chromodynamics (QCD) matter created in nuclear collisions at collider energies. Jets are reconstructed from charged particles using the anti-$k_{\rm T}$ jet algorithm and resolution parameter $R = 0.4$. The jets are measured in the pseudorapidity range $|η_{\rm{jet}}|<0.5$ and in three intervals of transverse momentum between 60 GeV/$c$ and 120 GeV/$c$. The measurement of the jet mass in central Pb-Pb collisions is compared to the jet mass as measured in p-Pb reference collisions, to vacuum event generators, and to models including jet quenching. It is observed that the jet mass in central Pb-Pb collisions is consistent within uncertainties with p-Pb reference measurements. Furthermore, the measured jet mass in Pb-Pb collisions is not reproduced by the quenching models considered in this letter and is found to be consistent with PYTHIA expectations within systematic uncertainties.
description: 26 pages, 11 captioned figures, 1 table, authors from page 21, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/3366
The Lawson-Hanson Algorithm with Deviation Maximization: Finite Convergence and Sparse Recovery
Creators: name: Dessole, Monica
name: Dell'Orto, Marco
name: Marcuzzi, Fabio
Publisher: name: arXiv
Year: 2021
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics
subject: G.1.3

description: In this work we apply the "deviation maximization", a new column selection strategy, to the Lawson-Hanson algorithm for the solution of NonNegative Least Squares (NNLS), devising a new algorithm we call Lawson-Hanson with Deviation Maximization (LHDM). This algorithm allows to exploit BLAS-3 operations, leading to higher performances. We show the finite convergence of this algorithm and explore the sparse recovery ability of LHDM. The results are presented with an extensive campaign of experiments, where we compare its performance against several $\ell_1$-minimization solvers. An implementation of the proposed algorithm is available on a public repository.
description: 30 pages
Necessary and sufficient stability conditions for integral delay systems
Creators: name: Ortiz, Reynaldo
name: Egorov, Alexey
name: Mondié, Sabine
Publisher: name: arXiv
Year: 2021
Subjects: subject: Systems and Control (eess.SY)
subject: Dynamical Systems (math.DS)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Mathematics

description: A Lyapunov-Krasovskii functional with prescribed derivative whose construction does not require the stability of the system is introduced. It leads to the presentation of stability/instability theorems. By evaluating the functional at initial conditions depending on the fundamental matrix we are able to present necessary and sufficient stability conditions expressed exclusively in terms of the delay Lyapunov matrix for integral delay systems. Some examples illustrate and validate the stability conditions.
description: This paper has been submitted to International Journal of Robust and Nonlinear Control
MSE estimates for multitaper spectral estimation and off-grid compressive sensing
Creators: name: Abreu, Luís Daniel
name: Romero, José Luis
Publisher: name: arXiv
Year: 2017
Subjects: subject: Information Theory (cs.IT)
subject: Statistics Theory (math.ST)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics

description: We obtain estimates for the Mean Squared Error (MSE) for the multitaper spectral estimator and certain compressive acquisition methods for multi-band signals. We confirm a fact discovered by Thomson [Spectrum estimation and harmonic analysis, Proc. IEEE, 1982]: assuming bandwidth $W$ and $N$ time domain observations, the average of the square of the first $K=2NW$ Slepian functions approaches, as $K$ grows, an ideal band-pass kernel for the interval $[-W,W]$. We provide an analytic proof of this fact and measure the corresponding rate of convergence in the $L^{1}$ norm. This validates a heuristic approximation used to control the MSE of the multitaper estimator. The estimates have also consequences for the method of compressive acquisition of multi-band signals introduced by Davenport and Wakin, giving MSE approximation bounds for the dictionary formed by modulation of the critical number of prolates.
description: 16 pages, 2 figures. (This article replaces arXiv: 1503.02991.)
Static and dynamic properties of Josephson weak links with singlet and triplet coupling
Creators: name: Moor, Andreas
name: Volkov, Anatoly F.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We theoretically study static and dynamic properties of short Josephson junctions (JJ) with singlet and triplet Josephson coupling. In singlet Josephson weak links, two singlet superconductors S are connected with each other by a normal film (N) or wire. Triplet JJs, which we denote S$_{\text{m}}$/N(F)/S$_{\text{m}}$, are formed by two singlet BCS superconductors covered by a thin layer of a weak ferromagnet F$_{\text{w}}$. These superconductors S$_{\text{m}}$ are separated from the N (or F) layer by spin filters, which pass electrons with only one spin orientation. The triplet Cooper pairs propagating from the left (right) superconductors S$_{\text{m}}$ differ from each other not only by polarizations, but also by chiralities. The latter is determined by the magnetization orientation in weak ferromagnets F$_{\text{w}}$. We obtain analytical formulas for the critical Josephson current in both types of the JJs. If chiralities of the triplet Cooper pairs penetrating into the N film in S$_{\text{m}}$/N(F)/S$_{\text{m}}$ JJs from the left and right S$_{\text{m}}$ are different, the Josephson current is not zero in the absence of the phase difference (spontaneous Josephson current). We also calculate the admittance $Y(Ω)$ for arbitrary frequencies $Ω$ in the case of singlet JJs and for low frequencies in the case of triplet JJs. At low temperatures $T$, the real part of the admittance $Y^{\prime}(Ω)$ in singlet JJs starts to increase from zero at ${\hbar Ω\geq Δ_{\text{sg}}}$, but at ${T \geq Δ_{\text{sg}}}$, it has a peak at low frequencies the magnitude of which is determined by inelastic processes. The subgap $Δ_{\text{sg}}$ depends on transparencies of the S/N interfaces and on the phase difference $2 χ_{0}$. The low-frequency peak in $Y^{\prime}(Ω)$ in triplet JJs disappears.
description: 11+ pages; 4 figures; published version
Fully self-consistent optimization of the Jastrow-Slater-type wave function using a similarity-transformed Hamiltonian
Creators: name: Ochi, Masayuki
Publisher: name: arXiv
Year: 2021
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: It has been well established that the Jastrow correlation factor can effectively capture the electron correlation effects, and thus, the efficient optimization of the many-body wave function including the Jastrow correlation factor is of great importance. For this purpose, the transcorrelated $+$ variational Monte Carlo (TC$+$VMC) method is one of the promising methods, where the one-electron orbitals in the Slater determinant and the Jastrow factor are self-consistently optimized in the TC and VMC methods, respectively. In particular, the TC method is based on similarity-transformation of the Hamitonian by the Jastrow factor, which enables the efficient optimization of the one-electron orbitals under the effective interaction. Through test calculations of some closed-shell atoms, He, Be, and Ne, we find that the total energy is in many cases systematically improved by using better Jastrow functions. We find that even a one-shot TC$+$VMC calculation, where the Jastrow parameters are optimized at the Hartree-Fock$+$VMC level, can yield partial benefits from orbital optimization. It is also suggested that one-shot TC$+$VMC can be a good alternative way for complex systems. Our study provides important insights for optimizing many-body wave function including the Jastrow correlation factor, which would be of great help for development of highly accurate electronic structure calculations.
description: 19 pages, 8 figures
Exotic Electroweak Signals in Twin Higgs
Creators: name: Cheng, Hsin-Chia
name: Salvioni, Ennio
name: Tsai, Yuhsin
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: The Twin Higgs model is the preeminent example of a theory of neutral naturalness, where the new particles that alleviate the little hierarchy problem are Standard Model (SM) singlets. The most promising collider search strategy, based on rare Higgs decays, is nevertheless not effective in significant regions of the parameter space of the low energy theory. This underlines the importance of phenomenological studies on ultraviolet completions of the Twin Higgs model, which must lie at a scale lower than 5-10 TeV. We pursue this course in the context of non-supersymmetric completions, focusing on exotic fermions that carry SM electroweak and twin color charges, as well as on exotic vectors that transform as the bi-fundamental of the electroweak or color groups. Both $Z_2$-preserving and $Z_2$-breaking mass spectra are considered for the exotic fermions. In the former case they must be heavier than $\sim 1$ TeV, but can still be sizably produced in the decays of the color bi-fundamental vector. In the $Z_2$-breaking scenario, the exotic fermions can have masses in the few hundred GeV range without significantly increasing the fine-tuning. Once pair-produced through the electroweak interactions, they naturally form bound states held together by the twin color force, which subsequently annihilate back to SM particles. The associated resonance signals are discussed in detail. We also outline the phenomenology of the electroweak bi-fundamental vectors, some of which mix with the SM $W$ and $Z$ and can therefore be singly produced in hadron collisions.
description: 36 pages, 9 figures; v2: version published in PRD, a few discussions extended to address referee's comments. References added
Pinpointing the Dominant Component of Contact Resistance to Atomically Thin Semiconductors
Creators: name: Ber, Emanuel
name: Grady, Ryan W.
name: Pop, Eric
name: Yalon, Eilam
Publisher: name: arXiv
Year: 2021
Subjects: subject: Applied Physics (physics.app-ph)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Achieving good electrical contacts is one of the major challenges in realizing devices based on atomically thin two-dimensional (2D) semiconductors. Several studies have examined this hurdle, but a universal understanding of the contact resistance and an underlying approach to its reduction are currently lacking. In this work we expose the shortcomings of the classical contact resistance model in describing contacts to 2D materials, and offer a correction based on the addition of a lateral pseudo-junction resistance component (Rjun). We use a combination of unique contact resistance measurements to experimentally characterize Rjun for Ni contacts to monolayer MoS2. We find that Rjun is the dominating component of the contact resistance in undoped 2D devices and show that it is responsible for most of the back-gate bias and temperature dependence. Our corrected model and experimental results help understand the underlying physics of state-of-the-art contact engineering approaches in the context of minimizing Rjun.
Domain percolation in a quenched ferromagnetic spinor condensate
Creators: name: Shitara, Nanako
name: Bir, Shreya
name: Blakie, P. Blair
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: We show that the easy-axis (EA) magnetic domains formed in a quenched ferromagnetic spinor condensate are described by percolation theory. We introduce a generalized spin rotation to vary the proportion of positive and negative EA domains, allowing us to explore domain percolation. Using simulations we investigate the finite-size scaling behaviour to extract the correlation length critical exponent and the transition point. We analyse the sensitivity of our results to the early-time dynamics of the system, the quadratic Zeeman energy, and the threshold condition used to define the positive (percolating) domains.
Search for leptophobic Z' bosons decaying into four-lepton final states in proton-proton collisions at sqrt(s) = 8 TeV
Creators: name: CMS Collaboration
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: A search for heavy narrow resonances decaying into four-lepton final states from cascade decays of a Z' boson has been performed using proton-proton collision data at sqrt(s) = 8 TeV collected by the CMS experiment, corresponding to an integrated luminosity of 19.7 inverse femtobarns. No excess of events over the standard model background expectation is observed. Upper limits for a benchmark model on the product of cross section and branching fraction for the production of these heavy narrow resonances are presented. The limit excludes leptophobic Z' bosons with masses below 2.5 TeV within the benchmark model. This is the first result to constrain a leptophobic Z' resonance in the four-lepton channel.
description: Replaced with the published version. Added the journal reference and DOI. All the figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/EXO-14-006 (CMS Public Pages)
M$_k$ models: the field theory connection
Creators: name: Fokkema, T.
name: Schoutens, K.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: The M$_k$ models for 1D lattice fermions are characterised by ${\cal N}=2$ supersymmetry and by an order-$k$ clustering property. This paper highlights connections with quantum field theories (QFTs) in various regimes. At criticality the QFTs are minimal models of ${\cal N}=2$ supersymmetric conformal field theory (CFT) - we analyse finite size spectra on open chains with a variety of supersymmetry preserving boundary conditions. Specific staggering perturbations lead to a gapped regime corresponding to massive ${\cal N}=2$ supersymmetric QFT with Chebyshev superpotentials. At `extreme staggering' we uncover a simple physical picture with degenerate supersymmetric vacua and mobile kinks. We connect this kink-picture to the Chebyshev QFTs and use it to derive novel CFT character formulas. For clarity the focus in this paper is on the simplest models, M$_1$, M$_2$ and M$_3$.
description: 44 pages, 7 figures, submission to SciPost, minor revision in v2
Towards Reducing Aleatoric Uncertainty for Medical Imaging Tasks
Creators: name: Sambyal, Abhishek Singh
name: Krishnan, Narayanan C.
name: Bathula, Deepti R.
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: In safety-critical applications like medical diagnosis, certainty associated with a model's prediction is just as important as its accuracy. Consequently, uncertainty estimation and reduction play a crucial role. Uncertainty in predictions can be attributed to noise or randomness in data (aleatoric) and incorrect model inferences (epistemic). While model uncertainty can be reduced with more data or bigger models, aleatoric uncertainty is more intricate. This work proposes a novel approach that interprets data uncertainty estimated from a self-supervised task as noise inherent to the data and utilizes it to reduce aleatoric uncertainty in another task related to the same dataset via data augmentation. The proposed method was evaluated on a benchmark medical imaging dataset with image reconstruction as the self-supervised task and segmentation as the image analysis task. Our findings demonstrate the effectiveness of the proposed approach in significantly reducing the aleatoric uncertainty in the image segmentation task while achieving better or on-par performance compared to the standard augmentation techniques.
description: Accepted in IEEE International Symposium on Biomedical Imaging (ISBI) 2022
Impacto das Emendas Impositivas sobre as Emendas de Relator
Creators: name: Rocha, Alexandre
Publisher: name: figshare
Year: 2022
Subjects: subject: 140215 Public Economics- Taxation and Revenue
subject: FOS: Economics and business

description: O retorno das emendas de relator foi um artifício para que os interesses do Executivo e do Legislativo voltassem a ficar alinhados, agora com a mediação das Presidências das duas Casas, após a introdução das emendas parlamentares com execução impositiva. O objetivo deste artigo é analisar as motivações e as circunstâncias que resultaram no uso desse artifício. [Poder360]
MPEC 2023-P64 : 2023 NC7
Creators: name: Minor Planet Center Staff
Publisher: name: The Minor Planet Center
Year: 2023
Subjects: subject: Small Solar System bodies
valueUri: http://astrothesaurus.org/uat/1469
subject: 2023 NC7

description: The Minor Planet Electronic Circulars contain information on unusual minor planets, routine data on comets and natural satellites, and occasional editorial announcements.  They are published on behalf of Division F of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Horizon fluff, semi-classical black hole microstates - Log-corrections to BTZ entropy and black hole/particle correspondence
Creators: name: Afshar, H.
name: Grumiller, D.
name: Sheikh-Jabbari, M. M.
name: Yavartanoo, H.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: According to the horizon fluff proposal microstates of a generic black hole belong to a certain subset of near horizon soft hairs that cannot be extended beyond the near horizon region. In [1,2] it was shown how the horizon fluff proposal works for AdS3 black holes. In this work we clarify further this picture by showing that BTZ black hole microstates are in general among the coherent states in the Hilbert space associated with conic spaces or their Virasoro descendants, provided we impose a (Bohr-type) quantization condition on the angular deficit. Thus BTZ black holes may be viewed as condensates (or solitonic states) of AdS3 particles. We provide canonical and microcanonical descriptions of the statistical mechanical system associated with BTZ black holes and their microstates, and relate them. As a further non-trivial check we show the horizon fluff proposal correctly reproduces the expected logarithmic corrections to the BTZ entropy.
description: 47pp, v2: added references, minor correction in section 6.1, results unchanged, v3: 51pp, added figures, references and clarifications, to appear in JHEP
Stochastic unraveling of positive quantum dynamics
Creators: name: Caiaffa, Matteo
name: Smirne, Andrea
name: Bassi, Angelo
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Stochastic unravelings represent a useful tool to describe the dynamics of open quantum systems and standard methods, such as quantum state diffusion (QSD), call for the complete positivity of the open-system dynamics. Here, we present a generalization of QSD, which also applies to positive, but not completely positive evolutions. The rate and the action of the diffusive processes involved in the unraveling are obtained by applying a proper transformation to the operators which define the master equation. The unraveling is first defined for semigroup dynamics and then extended to a definite class of time-dependent generators. We test our approach on a prototypical model for the description of exciton transfer, keeping track of relevant phenomena, which are instead disregarded within the standard, completely positive framework.
description: 9 pages, 2 figures
Thermospin effects in superconducting heterostructures
Creators: name: Bobkova, I. V.
name: Bobkov, A. M.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Recently thermally created pure spin currents were predicted for Zeeman-split superconductor/normal metal heterostructures. Here it is shown that this "thermospin" current can lead to an accumulation of a pure spin imbalance in a system. The thermally induced spin imbalance can reach the value of Zeeman splitting of the superconducting DOS and strongly influences superconductivity in the heterostructure. Depending on the temperature difference between the superconductor and the normal reservoir it can enhance the critical temperature of the superconductor or additionally suppress the zero-temperature superconducting state. The last possibility gives rise to an unusual superconducting state, which starts to develop at finite temperature.
description: extended and improved version
Fokker–Planck approach to neural networks and to decision problems
Creators: name: Vellmer, Sebastian
name: Lindner, Benjamin
Publisher: name: Humboldt-Universität zu Berlin
Year: 2021
Subjects: subject: 530 Physik

description: We review applications of the Fokker–Planck equation for the description of systems with event trains in computational and cognitive neuroscience. The most prominent example is the spike trains generated by integrate-and-fire neurons when driven by correlated (colored) fluctuations, by adaptation currents and/or by other neurons in a recurrent network. We discuss how for a general Gaussian colored noise and an adaptation current can be incorporated into a multidimensional Fokker–Planck equation by Markovian embedding for systems with a fire-and-reset condition and how in particular the spike-train power spectrum can be determined by this equation. We then review how this framework can be used to determine the self-consistent correlation statistics in a recurrent network in which the colored fluctuations arise from the spike trains of statistically similar neurons. We then turn to the popular drift-diffusion models for binary decisions in cognitive neuroscience and demonstrate that very similar Fokker–Planck equations (with two instead of only one threshold) can be used to study the statistics of sequences of decisions. Specifically, we present a novel two-dimensional model that includes an evidence variable and an expectancy variable that can reproduce salient features of key experiments in sequential decision making.
Investigating the Settling Dynamics of Cohesive Silt Particles With Particle-Resolving Simulations
Creators: name: Sun, Rui
name: Xiao, Heng
name: Sun, Honglei
Publisher: name: arXiv
Year: 2017
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Fluid Dynamics (physics.flu-dyn)
subject: Geophysics (physics.geo-ph)
subject: FOS: Physical sciences

description: The settling of cohesive sediment is ubiquitous in aquatic environments. In the settling process, the silt particles show behaviors that are different from non-cohesive particles due to the influence of inter-particle cohesive force. While it is a consensus that cohesive behaviors depend on the characteristics of sediment particles (e.g., Bond number, particle size distribution), little is known about the exact influence of these characteristics on the cohesive behaviors. In the present work, three-dimensional settling process is investigated numerically by using CFD--DEM (Computational Fluid Dynamics--Discrete Element Method). The inter-particle collision force, the van der Waals force, and the fluid--particle interaction forces are considered. The numerical model is used to simulate the hindered settling process of silt based on the experimental setup in the literature. The results obtained in the simulations, including the structural densities of the beds, the characteristic lines, and the particle terminal velocity, are in good agreement with the experimental observations in the literature. To the authors' knowledge, this is the first time that the influences of non-dimensional Bond number and particle polydispersity on the structural densities of silt beds have been investigated separately. The results demonstrate that the cohesive behavior of silt in the settling process is attributed to both the cohesion among silt particles themselves and the particle polydispersity. To guide to the macro-scale modeling of cohesive silt sedimentation, the collision frequency functions obtained in the numerical simulations are also presented based on the micromechanics of particles. The results obtained by using CFD--DEM indicate that the binary collision theory over-estimated the particle collision frequency in the flocculation process at high solid volume fraction.
Chiral Spin Condensation in a One-Dimensional Optical Lattice
Creators: name: Wu, Ying-Hai
name: Li, Xiaopeng
name: Sarma, S. Das
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We study a spinor (two-component) Bose gas confined in a one-dimensional double-valley optical lattice which has a double-well structure in momentum space. Based on field theory analysis, it is found that spinor bosons in the double-valley band may form a spin-charge mixed chiral spin quasicondensate under certain conditions. Our numerical calculations in a concrete $π$-flux triangular ladder system confirm the robustness of the chiral spin order against interactions and quantum fluctuations. This exotic atomic Bose-Einstein condensate exhibits spatially staggered spin loop currents without any charge dynamics despite the complete absence of spin-orbit coupling in the system, creating an interesting approach to atom spintronics. The entanglement entropy scaling allows us to extract conformal-field-theory central charge and establish the low-energy effective field theory for the chiral spin condensate as a two-component Luttinger liquid. Our predictions should be detectable in atomic experiments through spin-resolved time-of-flight techniques.
description: 5 pages, 4 figures
A Mechanism of Baryogenesis for Causal Fermion Systems
Creators: name: Finster, Felix
name: Jokel, Maximilian
name: Paganini, Claudio F.
Publisher: name: arXiv
Year: 2021
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: It is shown that the theory of causal fermion systems gives rise to a novel mechanism of baryogenesis. This mechanism is worked out computationally in globally hyperbolic spacetimes in a way which enables the quantitative study in concrete cosmological situations.
description: 50 pages, LaTeX, 7 figures, correction in formula (5.10)
High-Fidelity Preservation of Quantum Information During Trapped-Ion Transport
Creators: name: Kaufmann, Peter
name: Gloger, Timm F.
name: Kaufmann, Delia
name: Johanning, Michael
name: Wunderlich, Christof
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: A promising scheme for building scalable quantum simulators and computers is the synthesis of a scalable system using interconnected subsystems. A prerequisite for this approach is the ability to faithfully transfer quantum information between subsystems. With trapped atomic ions, this can be realized by transporting ions with quantum information encoded into their internal states. Here, we measure with high precision the fidelity of quantum information encoded into hyperfine states of a 171Yb+ ion during ion transport in a microstructured Paul trap. Ramsey spectroscopy of the ion's internal state is interleaved with up to 4000 transport operations over a distance of 280 μm each taking 12.8 μs. We obtain a state fidelity of 99.9994(+6/-7)per ion transport.
description: Supplemental Material included on page 6ff
A branch statistic for trees: Interpreting coefficients of the characteristic polynomial of braid deformations
Creators: name: Deshpande, Priyavrat
name: Menon, Krishna
Publisher: name: arXiv
Year: 2021
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 52C35, 05C30

description: A hyperplane arrangement in $\mathbb{R}^n$ is a finite collection of affine hyperplanes. The regions are the connected components of the complement of these hyperplanes. By a theorem of Zaslavsky, the number of regions of a hyperplane arrangement is the sum of coefficients of its characteristic polynomial. Arrangements that contain hyperplanes parallel to subspaces whose defining equations are $x_i - x_j = 0$ form an important class called the deformations of the braid arrangement. In a recent work, Bernardi showed that regions of certain deformations are in one-to-one correspondence with certain labeled trees. In this article, we define a statistic on these trees such that the distribution is given by the coefficients of the characteristic polynomial. In particular, our statistic applies to well-studied families like extended Catalan, Shi, Linial and semiorder.
description: Section 4 restructured, other minor changes, final version
Direct Bounds on Heavy Top-Like Quarks With Standard and Exotic Decays
Creators: name: Chala, Mikael
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: Heavy vector-like quarks with electric charge $Q=2/3$ (also called \textit{heavy tops}) appear naturally in many extensions of the Standard Model. Although these typically predict the existence of further particles below the TeV scale, direct searches for heavy tops have been performed assuming that they decay only into SM particles. The aim of this paper is to overcome this situation. We consider the most constraining experimental LHC searches for vector-like quarks, including analyses of the 36 fb$^{-1}$ of data collected in the latest run at 13 TeV of center of mass energy, as well as searches sensitive to heavy tops decaying into a new scalar, $S$. Combining all these, we derive bounds for arbitrary values of the heavy top branching ratios. A simple code that automatizes this process is also provided. At the physics level, we demonstrate that bounds on heavy tops are not inevitably weaker in the presence of new light scalars. We find that heavy tops with masses below $\sim 900$ GeV are excluded by direct searches, independently of whether they decay into $Zt, Ht, Wb$ or $St$ (with $S$ giving either missing energy of bottom quarks) or into any combination of them.
description: 26 pages, 9 figures. V2: matches published version
Tell me what you see: A zero-shot action recognition method based on natural language descriptions
Creators: name: Estevam, Valter
name: Laroca, Rayson
name: Menotti, David
name: Pedrini, Helio
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: This paper presents a novel approach to Zero-Shot Action Recognition. Recent works have explored the detection and classification of objects to obtain semantic information from videos with remarkable performance. Inspired by them, we propose using video captioning methods to extract semantic information about objects, scenes, humans, and their relationships. To the best of our knowledge, this is the first work to represent both videos and labels with descriptive sentences. More specifically, we represent videos using sentences generated via video captioning methods and classes using sentences extracted from documents acquired through search engines on the Internet. Using these representations, we build a shared semantic space employing BERT-based embedders pre-trained in the paraphrasing task on multiple text datasets. The projection of both visual and semantic information onto this space is straightforward, as they are sentences, enabling classification using the nearest neighbor rule. We demonstrate that representing videos and labels with sentences alleviates the domain adaptation problem. Additionally, we show that word vectors are unsuitable for building the semantic embedding space of our descriptions. Our method outperforms the state-of-the-art performance on the UCF101 dataset by 3.3 p.p. in accuracy under the TruZe protocol and achieves competitive results on both the UCF101 and HMDB51 datasets under the conventional protocol (0/50\% - training/testing split). Our code is available at https://github.com/valterlej/zsarcap.
description: Published at Multimedia Tools and Applications
Gravitationally lensed quasars in the reionization era: the prospective for the Roman Telescope
Creators: name: Yue, Minghao
Publisher: name: Zenodo
Year: 2023
Subjects: Galaxy Surveys at High Redshift

description: High-redshift quasars trace the extreme phases of SMBH and galaxy evolution at cosmic dawn. They are hosted by the most massive galaxies at their redshifts and harbor colossal SMBHs (with M_BH >~ 10^9 M_sun). With the help of lensing magnification, high-redshift gravitationally lensed quasars offer the best opportunity to conduct in-depth studies of high-redshift SMBHs and their host galaxies. However, our knowledge regarding lensed quasars at z>5 remains highly restricted due to the limited depth and sky coverage of current sky surveys. The upcoming sky surveys (like Euclid, LSST, and Roman) are expected to produce the first large sample (>~50 at z>5.5) of lensed quasars in the reionization era. In particular, the spectroscopic capacity of Roman makes it the most promising mission for building a complete sample of high-redshift lensed quasars. These lensed quasars will be valuable objects for follow-up observations using JWST and ALMA, enabling crucial experiments not feasible with non-lensed quasars. Specifically, these lensed quasars will allow us to accurately measure the quasar luminosity function, explore the faint end of high-redshift quasars, and characterize the small-scale structures (down to ~50 pc) of the quasar host galaxies.
The $Z_2 \times Z_2$-graded Lie superalgebras $pso(2n+1|2n)$ and $pso(\infty|\infty)$, and parastatistics Fock spaces
Creators: name: Stoilova, N. I.
name: Van der Jeugt, J.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mathematical Physics (math-ph)
subject: High Energy Physics - Theory (hep-th)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The parastatistics Fock spaces of order $p$ corresponding to an infinite number of parafermions and parabosons with relative paraboson relations are constructed. The Fock spaces are lowest weight representations of the $Z_2 \times Z_2$-graded Lie superalgebra $pso(\infty|\infty)$, with a basis consisting of row-stable Gelfand-Zetlin patterns.
description: arXiv admin note: text overlap with arXiv:1904.00061
Repulsion in low temperature $β$-ensembles
Creators: name: Ameur, Yacin
Publisher: name: arXiv
Year: 2017
Subjects: subject: Probability (math.PR)
subject: Mathematical Physics (math-ph)
subject: Complex Variables (math.CV)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: We prove a result on separation of particles in a two-dimensional Coulomb plasma, which holds provided that the inverse temperature $β$ satisfies $β>1$. For large $β$, separation is obtained at the same scale as the conjectural Abrikosov lattice optimal separation.
description: A previous union bound mistake on p 8 was corrected. As a consequence, the main results are somewhat modified