cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
A unified-description of curvature, torsion, and non-metricity of the metric-affine geometry with the Möbius representation
Creators: name: Tomonari, Kyosuke
Publisher: name: arXiv
Year: 2023
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: We establish the mathematical fundamentals for a unified description of curvature, torsion, and non-metricity 2-forms in the way extending the so-called Möbius representation of the affine group, which is the method to convert the semi-direct product into the ordinary matrix product, to revive the fertility of gauge theories of gravity. First of all, we illustrate the basic concepts for constructing the metric-affine geometry. Then the curvature and torsion 2-forms are described in a unified manner by using the Cartan connection of the Möbius representation of the affine group. In this unified-description, the curvature and torsion are derived by Cartan's structure equation with respect to a common connection 1-form. After that, extending the Möbius representation, the dilation and shear 2-forms, or equivalently, the non-metricity 2-form, are introduced in the same unified manner. Based on the unified-description established in this paper, introducing a new group parametrization and applying the Inönü-Wigner group contraction to the full theory, the relationships among symmetries, geometric quantities, and geometries are investigated with respect to the three gauge groups: the metric-affine group and its extension, and an extension of the (anti)-de Sitter group in which the non-metricity exists. Finally, possible applications to theories of gravity are briefly discussed.
description: 29 pages. v2: 31 pages, moved some topics to appendix, added comments v3: 33 pages, added references and comments. Accepted version in IJGMMP
Le Sommet UE-Afrique 2021 : Quo vadis, compte tenu du Brexit et de la Covid-19
Creators: name: Kohnert, Dirk
Publisher: name: Zenodo
Year: 2021
Subjects: Sommet UE-Afrique
Covid-19
Brexit
Corona
Afrique
UE

description: ABSTRACT & RÉSUMÉ : Every three years, the AU-EU summit reunites African and EU leaders to outline the future direction of cooperation. The 6th summit had been to reaffirm and renew the partnership between the two blocks already in October 2020, but it was pushed back to the first quarter of 2021 or even later due to COVID-19 crisis. Besides, Brussels had to deal with its own post-Brexit situation and its repercussions on EU-Africa relations, excluding the UK. African states, for their part, wanted to renegotiate the EU-Africa partnership and to balance it with new promising Post-Brexit visions of the British premier Johnson about increased economic ties with the African Angloshere. China and other global players compete with the EU and its member states in the new scramble for African resources. Given that Africa is increasingly courted by other partners it could be inclined to successively limit its relations with the EU and see it as a mere provider of aid and security against Islamic terrorism. This trend was reinforced by the fact that the new EU-Africa strategy still hasn't been approved by EU member states. And a timely replacement of the Cotonou Agreement, which expires in November 2021, is open to question. _________________________________________________________________________ RÉSUMÉ : Tous les trois ans, le sommet UA-UE réunit les dirigeants africains et européens pour définir l'orientation future de la coopération. Le 6e sommet devait réaffirmer et renouveler le partenariat entre les deux blocs déjà en octobre 2020, mais il a été repoussé au premier trimestre 2021, ou même plus tard, en raison de la crise du COVID-19. En outre, Bruxelles a dû faire face à sa propre situation post-Brexit, compte tenu l'exclusion du Royaume-Uni, et à ses répercussions sur les relations UE-Afrique. Les États africains, pour leur part, souhaitaient renégocier le partenariat UE-Afrique, et l'équilibrer avec les nouvelles visions post-Brexit prometteuses du Premier ministre britannique Johnson sur le renforcement des liens économiques avec l'Anglosphère africaine. La Chine et d'autres acteurs mondiaux sont en concurrence avec l'UE et ses États membre dans la nouvelle ruée vers les ressources africaines. Étant donné que l'Afrique est de plus en plus courtisée par d'autres partenaires, elle pourrait être encline à limiter successivement ses relations avec l'UE et à la considérer comme un simple fournisseur d'aide et de sécurité contre le terrorisme islamique. Cette tendance a été renforcée par le fait que la nouvelle stratégie UE-Afrique n'a toujours pas été approuvée par les États membres de l'UE. Et un remplacement opportun de l'accord de Cotonou, qui expire en novembre 2021, est sujet à caution.
description: French version of Kohnert, Dirk (2021): The EU-Africa summit 2021 : Quo vadis, in the light of Brexit and Corona
GroupMath: A Mathematica package for group theory calculations
Creators: name: Fonseca, Renato M.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: GroupMath is a Mathematica package which performs several calculations related to semi-simple Lie algebras and the permutation groups, both of which are important in particle physics as well as in other areas of research.
description: Describes version 1.1 of the program. Code available on http://renatofonseca.net/groupmath
Phase diagram and thermodynamics of the three-dimensional Bose-Hubbard model
Creators: name: Capogrosso-Sansone, B.
name: Prokof'ev, N. V.
name: Svistunov, B. V.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We report results of quantum Monte Carlo simulations of the Bose-Hubbard model in three dimensions. Critical parameters for the superfluid-to-Mott-insulator transition are determined with significantly higher accuracy than it has been done in the past. In particular, the position of the critical point at filling factor n=1 is found to be at (U/t)_c = 29.34(2), and the insulating gap Delta is measured with accuracy of a few percent of the hopping amplitude t. We obtain the effective mass of particle and hole excitations in the insulating state--with explicit demonstration of the emerging particle-hole symmetry and relativistic dispersion law at the transition tip--along with the sound velocity in the strongly correlated superfluid phase. These parameters are the necessary ingredients to perform analytic estimates of the low temperature (T << Delta) thermodynamics in macroscopic samples. We present accurate thermodynamic curves, including these for specific heat and entropy, for typical insulating (U/t=40) and superfluid (t/U=0.0385) phases. Our data can serve as a basis for accurate experimental thermometry, and a guide for appropriate initial conditions if one attempts to use interacting bosons in quantum information processing.
description: 11 pages, 13 figures
Reviving chaotic inflation with fermion production: a supergravity model
Creators: name: Roberts, Michael A.
name: Sorbo, Lorenzo
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Processes of particle production during inflation can increase the amplitude of the scalar metric perturbations. We show that such a mechanism can naturally arise in supergravity models where an axion-like field, whose potential is generated by monodromy, drives large field inflation. In this class of models one generally expects instanton-like corrections to the superpotential. We show, by deriving the equations of motion in models of supergravity with a stabilizer, that such corrections generate an interaction between the inflaton and its superpartner. This inflaton-inflatino interaction term is rapidly oscillating, and can lead to copious production of fermions during inflation, filling the Fermi sphere up to momenta much larger than the Hubble parameter. In their turn, those fermions source inflaton fluctuations, increasing their amplitude, and effectively lowering the tensor-to-scalar ratio for the model, as discussed in [1, 2]. This allows, in particular, to bring the model where the inflaton potential is quadratic (plus negligibly small instanton corrections) to agree with all existing observations.
description: 13 pages, 3 figures
Combination of Multi-Modal Imaging and Neurophysiology to Improve Targeting Accuracy and Outcome in Deep Brain Stimulation for Movement Disorders
Creators: name: Moran, Paul
Publisher: name: UH Research Archive
Year: 2021
Subjects: Parkinson's disease
Lead DBS
Deep brain stimulation
MRI
DTI
Matlab
Electrode

description: A study was conducted to observe the positioning of two sets of electrodes in fourteen patients with Parkinson’s disease (PD). The purpose was to potentially optimise electrode positioning and parameters with the goal of possibly benefiting patient outcome. Boston scientific electrodes were the multi-directional electrodes (also known as directional) and Medtronic 3389 were the conventional electrodes, each set had been previously surgically inserted into PD patients with pre- and post-operative imaging data available. The corresponding data was input into Lead DBS software to identify the hypothetical electrode position in silico. A target point within the most central point of the motor region of subthalamic nucleus (mSTN) was selected with the corresponding distance measured from the active contact of each patient electrode. The mean electrode distance observed from the target point to active contact in all patients was (right) 6.52 millimeter (mm) (SD=2.75, SE=0.83) and (left) 5.91mm (SD=2.83, SE= 0.82). The mean voltage was (right) 1.36V (SD=0.74, SE=0.2) and (left) 1.64V (SD=0.89, SE=0.25). No UPDRS data was available due to limited access to databases as a result of travel restrictions imposed rendering the study qualitative in nature. It was not possible to determine what electrode would be more successful to alleviate symptoms given the small cohort in each arm of the study. It was also not possible to determine if Diffusion tensor imaging (DTI) could be used as a tool in aiding in the reduction of volume of tissue activated outside of the desired area again due to low numbers of DTI data sets available. This study was able to optimize electrode parameters within Lead-DBS; however, this could not be replicated in a clinical setting as further research would be required to validate the results of this study. No firm conclusion can be drawn between the advantages and disadvantages of each type of electrode.
Quasi-normal Modes of Electromagnetic Perturbations of Four-Dimensional Topological Black Holes with Scalar Hair
Creators: name: Koutsoumbas, George
name: Musiri, Suphot
name: Papantonopoulos, Eleftherios
name: Siopsis, George
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We study the perturbative behaviour of topological black holes with scalar hair. We calculate both analytically and numerically the quasi-normal modes of the electromagnetic perturbations. In the case of small black holes we find evidence of a second-order phase transition of a topological black hole to a hairy configuration.
description: v2: 19 pages, 2 figures, added references, improved discussion, to appear in JHEP
Spectroscopic classification, variability and SED of the Fermi-detected CSS 3C 286: the radio-loudest NLS1 galaxy?
Creators: name: Yao, Su
name: Komossa, S.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: 3C 286 is a well-known calibrator source in radio astronomy. It is also one of very few compact steep-spectrum sources (CSS) detected in $γ$-rays. Here, we perform a detailed spectroscopic and variability analysis and present the first quasi-simultaneous optical to X-ray spectral energy distribution in order to reveal physical mechanisms which dominate its emission at different wavelengths, and arrive at a reliable optical source classification. The first main result of our study reveals several pitfalls when applying simple broad- or narrow-line Seyfert 1 (BLS1 or NLS1) classification criteria which only look at the [OIII]-H$β$ complex. [OIII] and H$β$ can be dominated by the same outflow components, in which case FWHM(H$β$) is no reliable classification criterion, and extinction by intrinsic or intervening material can make the highest-velocity H$β$ component undetectable. After careful combination of all information from UV-optical spectra along with multi-wavelength data, we confirm that 3C 286 can be classified as NLS1 galaxy, with line properties and SMBH mass (of order 10$^{8}$ M$_{\odot}$ and accreting near the Eddington limit) close to the BLS1 regime, making it an important borderline object. The quasi-simultaneous SED taken with $swift$ shows a sharp rise in the optical-UV, implying the presence of a strong accretion-disk component with EUV excess, consistent with emission-line diagnostics. Finally, we report the discovery of X-ray variability of 3C 286, plausibly dominated by jet emission, and variable by at least a factor $\sim4$. This result suggests to exercise caution when using 3C 286 as radio calibrator in high-resolution radio VLBI observations.
description: 10 pages, 4 figures, MNRAS accepted
The Production of Phygital Social Spaces: a Study on the Influential Factors that Foster New Interactions amongst Second-Generation British Nigerian Youth
Creators: name: Onafuye, Rebecca Ayotunde
Publisher: name: UH Research Archive
Year: 2021
Subjects: Phygital
Digital space
Physical space
Thirdspace
Digital culture
Youth culture
Social culture
Festivals
Social media
Communities

description: British Nigerian youths use of social media is undoubtedly altering the characteristics of urban festival landscapes, which no longer can be described merely as a physical construct. Shifts in the space-making paradigm have been caused by the interplay of physical and digital interactions performed by these youths and from a macro perspective, which as a result formulates a homogenous visual of a new dimensional space (Kirsch, 1995; Salinas, 2014a). The aim of this study is to illustrate and analyse the production of new phygital space through the ways youths interact within festival landscapes. In the context of this Doctoral Dissertation, the concept of phygital is used to describe a unique and interactive experience, birthed through the intersection between physical spatial objects and the use of digital technologies. Through the analysis of 1974 Henri Lefebvre’s conceptual triad as a foundation for the development in space-making, this research also aims to articulate the physical, digital and socio-cultural influences of youths interaction and formation of hybrid space (Stikker, 2013). Various researchers like Ciolfi (2004), Benedikt (1992), Dyson (1998) and others, have argued that physical and digital models do not seamlessly interlock with one another. However, the advancement in digital technologies and social media suggests otherwise, calling for research to suggest how both dimensions of space, and its inhabitants can coexist and interact within an existing landscape. Following on from an in-depth and critical narrative (in Chapter 2), this study uses qualitative and quantitative data of youth in real-life social settings to reimagine the role of the festival landscape and youth in the construction of phygital space. This is accomplished through an extension of Lefebvre’s spatial triad to develop a visual framework to show the social construction of phygital space. Furthermore, an in-depth investigation is made to explore the socio-cultural nuances to suggest a slightly divisive but beneficial approach to new hybrid space-making. The findings of this research illustrate the physical, digital and socio-cultural factors that influence social interactions amongst British Nigerian youths in festivals. In an attempt to depict the contemporary interactions of youths usage of digital media, new notions of space and culture emerge as the forefront of such communication. For instance the concept of instagrammable space and the #forusbyus culture emerges in the latter chapters, as a predominate factor of hybrid space-making. It is this notion and others that suggests that phygital space is socially produced.
All-Optical Domain Inversion in LiNbO3 Crystals by Visible Continuous-Wave Laser Irradiation
Creators: name: Sebastián-Vicente, Carlos
name: Imbrock, Jörg
name: Laubrock, Simon
name: Caballero-Calero, Olga
name: García-Cabañes, Angel
name: Carrascosa, Mercedes
Publisher: name: arXiv
Year: 2023
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Applied Physics (physics.app-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: LiNbO3 is a distinguished multifunctional material where ferroelectric domain engineering is of paramount importance. This degree of freedom of the spontaneous polarization remarkably enhances the applicability of LiNbO3, for instance in nonlinear photonics. However, conventional electrical poling suffers from several drawbacks. Namely, the lithographic patterning of electrodes is cumbersome and expensive, and the spatial resolution is constrained. In this work, we report the first method for all-optical domain inversion of LiNbO3 crystals using continuous-wave visible light. While we mainly focus on iron-doped LiNbO3, the applicability of the method is also showcased in undoped congruent LiNbO3. The technique is outstandingly simple, low-cost and readily accessible. It relies on ubiquitous elements: a light source with low/moderate power, basic optics and a conductive surrounding medium, e.g. water. Light-induced domain inversion is unequivocally demonstrated and characterized by combination of several experimental techniques: pyroelectric trapping of charged microparticles, selective chemical etching, surface topography profilometry, scanning electron microscopy and 3D Cerenkov microscopy. The influence of light intensity, exposure time, laser spot size and surrounding medium is thoroughly studied. Overall, our all-optical method offers straightforward implementation of LiNbO3 ferroelectric domain engineering, potentially sparking new research endeavors aimed at novel optoelectronic applications of photovoltaic LiNbO3 platforms.
On a family of Self-Affine IFS whose attractors have a non-fractal top
Creators: name: Hare, Kevin G.
name: Sidorov, Nikita
Publisher: name: arXiv
Year: 2021
Subjects: subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics

description: Let $0< λ< μ<1$ and $λ+μ>1$. In this note we prove that for the vast majority of such parameters the top of the attractor $A_{λ,μ}$ of the IFS $\{(λx,μy), (μx+1-μ, λy+1-λ)\}$ is the graph of a continuous, strictly increasing function. Despite this, for most parameters, $A_{λ, μ}$ has a box dimension strictly greater than 1, showing that the upper boundary is not representative of the complexity of the fractal. Finally, we prove that if $λμ\ge 2^{-1/6}$, then $A_{λ,μ}$ has a non-empty interior.
description: 9 figures
A simple environment-dependent overlap potential and Cauchy violation in solid argon
Creators: name: Aoki, Masato
name: Kurokawa, Tatsuya
Publisher: name: arXiv
Year: 2007
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We develop an analytic and environment-dependent interatomic potential for the overlap repulsion in solid argon, based on an approximate treatment of the non-orthogonal Tight-Binding theory for the closed-shell systems. The present model can well reproduce the observed elastic properties of solid argon including Cauchy violation at high pressures, yet very simple. A useful and novel analysis is given to show how the elastic properties are related to the environment-dependence incorporated into a generic pairwise potential. The present study has a close link to the broad field of computational materials science, in which the inclusion of environment dependence in short-ranged repulsive part of a potential model is sometimes crucial in predicting the elastic properties correctly.
description: 10 pages, 3 figures
The role of context in the perception of emotion from facial expression
Creators: name: Carrol, James M.
Publisher: name: University of British Columbia
Year: 2009

description: In studies of emotion perception, an emphasis has been placed on the importance of facial information (Ekman, Friesen, and Ellsworth, 1972). One line of research suggests that facial information dominates contextual information in the perception of emotion (Frijda 1968; Watson, 1972; Walbott, 1988). The general procedure in this type of research has been to provide a scenario (context) in which a person may exhibit an emotion and then to show a picture of presumably their facial expression in that situation. According to previous research, when the face and context provide discrepant information, subjects' judgments tend to resemble the facial information more than the contextual information. The goal of the present studies was to examine 1) whether contextual stimuli could be created to dominate facial expressions of basic emotions and 2) whether the linear model assumed in research in cue dominance is an appropriate description of how emotion is perceived from face and context. Three studies were conducted using a similar procedure to the one described above. Study 1 showed that context dominance could occur for contexts referring to basic emotions. Study showed that context dominance could occur for contexts referring to non-basic emotions. Study 3 showed that judgments of face and context combined are not necessarily linearly related to judgments of face and context alone.
A stochastic representation for the Poisson-Vlasov equation
Creators: name: Mendes, R. Vilela
name: Cipriano, Fernanda
Publisher: name: arXiv
Year: 2006
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: A stochastic representation for the solutions of the Poisson-Vlasov equation is obtained. The representation involves both an exponential and a branching process. The stochastic representation, besides providing an alternative existence proof and an intuitive characterization of the solutions, may also be used to obtain an intrinsic definition of the fluctuations.
description: 9 Pages, 1 figure, VLASOVIA 2006
Dreaming of Electrical Waves: Generative Modeling of Cardiac Excitation Waves using Diffusion Models
Creators: name: Baranwal, Tanish
name: Lebert, Jan
name: Christoph, Jan
Publisher: name: arXiv
Year: 2023
Subjects: subject: Medical Physics (physics.med-ph)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Image and Video Processing (eess.IV)
subject: Biological Physics (physics.bio-ph)
subject: Tissues and Organs (q-bio.TO)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Biological sciences

description: Electrical waves in the heart form rotating spiral or scroll waves during life-threatening arrhythmias such as atrial or ventricular fibrillation. The wave dynamics are typically modeled using coupled partial differential equations, which describe reaction-diffusion dynamics in excitable media. More recently, data-driven generative modeling has emerged as an alternative to generate spatio-temporal patterns in physical and biological systems. Here, we explore denoising diffusion probabilistic models for the generative modeling of electrical wave patterns in cardiac tissue. We trained diffusion models with simulated electrical wave patterns to be able to generate such wave patterns in unconditional and conditional generation tasks. For instance, we explored the diffusion-based i) parameter-specific generation, ii) evolution and iii) inpainting of spiral wave dynamics, including reconstructing three-dimensional scroll wave dynamics from superficial two-dimensional measurements. Further, we generated arbitrarily shaped bi-ventricular geometries and simultaneously initiated scroll wave patterns inside these geometries using diffusion. We characterized and compared the diffusion-generated solutions to solutions obtained with corresponding biophysical models and found that diffusion models learn to replicate spiral and scroll waves dynamics so well that they could be used for data-driven modeling of excitation waves in cardiac tissue. For instance, an ensemble of diffusion-generated spiral wave dynamics exhibits similar self-termination statistics as the corresponding ensemble simulated with a biophysical model. However, we also found that diffusion models {produce artifacts if training data is lacking, e.g. during self-termination,} and `hallucinate' wave patterns when insufficiently constrained.
Thermal effects in spin torque switching of perpendicular magnetic tunnel junctions at cryogenic temperatures
Creators: name: Rehm, Laura
name: Wolf, Georg
name: Kardasz, Bartek
name: Cogulu, Egecan
name: Chen, Yizhang
name: Pinarbasi, Mustafa
name: Kent, Andrew D.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Applied Physics (physics.app-ph)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Temperature plays an important role in spin torque switching of magnetic tunnel junctions causing magnetization fluctuations that decrease the switching voltage but also introduce switching errors. Here we present a systematic study of the temperature dependence of the spin torque switching probability of state-of-the-art perpendicular magnetic tunnel junction nanopillars (40 to 60 nm in diameter) from room temperature down to 4 K, sampling up to a million switching events. The junction temperature at the switching voltage---obtained from the thermally assisted spin torque switching model---saturates at temperatures below about 75 K, showing that junction heating is significant below this temperature and that spin torque switching remains highly stochastic down to 4 K. A model of heat flow in a nanopillar junction shows this effect is associated with the reduced thermal conductivity and heat capacity of the metals in the junction.
description: 7 pages, 4 figures, 1 table, submitted to peer-reviewed journal
On correspondences of a K3 surface with itself. III
Creators: name: Madonna, C. G.
name: Nikulin, Viacheslav V.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics

description: Let $X$ be a K3 surface, and $H$ its primitive polarization of the degree $H^2=2rs$, $r,s\ge 1$. The moduli space of sheaves over $X$ with the isotropic Mukai vector $(r,H,s)$ is again a K3 surface, $Y$. In math.AG/0206158, math.AG/0304415 and math.AG/0307355 (in general) we gave necessary and sufficient conditions in terms of Picard lattice $N(X)$ of $X$ when $Y$ is isomorphic to $X$, under the additional condition $H\cdot N(X)=\bz$. Here we show that these conditions imply existence of an isomorphism between $Y$ and $X$ which is a composition of some universal isomorphisms between moduli of sheaves over $X$, and Tyurin's isomorphsim between moduli of sheaves over $X$ and $X$ itself. It follows that for a general K3 surface $X$ with $H\cdot N(X)=\bz$ and $Y\cong X$, there exists an isomorphism $Y\cong X$ which is a composition of the universal and the Tyurin's isomorphisms. This generalizes our recent results math.AG/0605362 for $r=s=2$ on similar subject.
description: 12 pages
Homogeneous versus Spiral Phases of Hole-doped Antiferromagnets: A Systematic Effective Field Theory Investigation
Creators: name: Brügger, C.
name: Hofmann, C. P.
name: Kämpfer, F.
name: Pepe, M.
name: Wiese, U. -J.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: Using the low-energy effective field theory for magnons and holes -- the condensed matter analog of baryon chiral perturbation theory for pions and nucleons in QCD -- we study different phases of doped antiferromagnets. We systematically investigate configurations of the staggered magnetization that provide a constant background field for doped holes. The most general configuration of this type is either constant itself or it represents a spiral in the staggered magnetization. Depending on the values of the low-energy parameters, a homogeneous phase, a spiral phase, or an inhomogeneous phase is energetically favored. The reduction of the staggered magnetization upon doping is also investigated.
description: 35 pages, 5 figures
Finite particle number description of neutron matter using the unitary correlation operator and high-momentum pair methods
Creators: name: Wan, Niu
name: Myo, Takayuki
name: Xu, Chang
name: Toki, Hiroshi
name: Horiuchi, Hisashi
name: Lyu, Mengjiao
Publisher: name: arXiv
Year: 2020
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: By using bare Argonne V4' (AV4'), V6' (AV6'), and V8' (AV8') nucleon-nucleon (NN) interactions respectively, the nuclear equations of state (EOSs) for neutron matter are calculated with the unitary correlation operator and high-momentum pair methods. The neutron matter is described under a finite particle number approach with magic number $N=66$ under a periodic boundary condition. The central short-range correlation coming from the short-range repulsion in the NN interaction is treated by the unitary correlation operator method (UCOM) and the tensor correlation and spin-orbit effects are described by the two-particle two-hole (2p2h) excitations of nucleon pairs, in which the two nucleons with a large relative momentum are regarded as a high-momentum pair (HM). With the 2p2h configurations increasing, the total energy per particle of neutron matter is well converged under this UCOM+HM framework. By comparing the results calculated with AV4', AV6', and AV8' NN interactions, the effects of the short-range correlation, the tensor correlation, and the spin-orbit coupling on the density dependence of the total energy per particle of neutron matter are demonstrated. Moreover, the contribution of each Hamiltonian component to the total energy per particle is discussed. The EOSs of neutron matter calculated within the present UCOM+HM framework agree with the calculations of six different microscopic many-body theories, especially in agreement with the auxiliary field diffusion Monte Carlo calculations.
description: 13 pages, 6 figures, 3 tables
Characterization of entanglement on superconducting quantum computers of up to 414 qubits
Creators: name: Kam, John F
name: Kang, Haiyue
name: Hill, Charles D
name: Mooney, Gary J
name: Hollenberg, Lloyd C L
Publisher: name: arXiv
Year: 2023
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: As quantum technology advances and the size of quantum computers grow, it becomes increasingly important to understand the extent of quality in the devices. As large-scale entanglement is a quantum resource crucial for achieving quantum advantage, the challenge in its generation makes it a valuable benchmark for measuring the performance of universal quantum devices. In this work, we study entanglement in Greenberger-Horne-Zeilinger (GHZ) and graph states prepared on the range of IBM Quantum devices. We generate GHZ states and investigate their coherence times with respect to state size and dynamical decoupling techniques. A GHZ fidelity of $0.519 \pm 0.014$ is measured on a 32-qubit GHZ state, certifying its genuine multipartite entanglement (GME). We show a substantial improvement in GHZ decoherence rates for a 7-qubit GHZ state after implementing dynamical decoupling, and observe a linear trend in the decoherence rate of $α=(7.13N+5.54)10^{-3}μs^{-1}$ for up to $N=15$ qubits, confirming the absence of superdecoherence. Additionally, we prepare and characterize fully bipartite entangled native graph states on 22 superconducting quantum devices with qubit counts as high as 414 qubits, all active qubits of the 433-qubit IBM Osprey device. Analysis of the decay of 2-qubit entanglement within the prepared states shows suppression of coherent noise signals with the implementation of dynamical decoupling techniques. Additionally, we observe that the entanglement in some qubit pairs oscillates over time, which is likely caused by residual ZZ-interactions. Characterizing entanglement in native graph states, along with detecting entanglement oscillations, can be an effective approach to low-level device benchmarking that encapsulates 2-qubit error rates along with additional sources of noise, with possible applications to quantum circuit compilation.
description: 25 pages, 21 figures
A method for nonlinear modal analysis and synthesis: Application to harmonically forced and self-excited mechanical systems
Creators: name: Krack, Malte
name: Scheidt, Lars Panning-von
name: Wallaschek, Jörg
Publisher: name: arXiv
Year: 2021
Subjects: subject: Numerical Analysis (math.NA)
subject: Computational Engineering, Finance, and Science (cs.CE)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences

description: The recently developed generalized Fourier-Galerkin method is complemented by a numerical continuation with respect to the kinetic energy, which extends the framework to the investigation of modal interactions resulting in folds of the nonlinear modes. In order to enhance the practicability regarding the investigation of complex large-scale systems, it is proposed to provide analytical gradients and exploit sparsity of the nonlinear part of the governing algebraic equations. A novel reduced order model (ROM) is developed for those regimes where internal resonances are absent. The approach allows for an accurate approximation of the multi-harmonic content of the resonant mode and accounts for the contributions of the off-resonant modes in their linearized forms. The ROM facilitates the efficient analysis of self-excited limit cycle oscillations, frequency response functions and the direct tracing of forced resonances. The ROM is equipped with a large parameter space including parameters associated with linear damping and near-resonant harmonic forcing terms. An important objective of this paper is to demonstrate the broad applicability of the proposed overall methodology. This is achieved by selected numerical examples including finite element models of structures with strongly nonlinear, non-conservative contact constraints.
Long Gamma Ray Bursts from Quark Stars
Creators: name: Haensel, P.
name: Zdunik, J. L.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: If strange quark matter (SQM) is the true ground state of hadronic matter, then conversion of neutron stars (NS) into quark stars (QS) could release some 10^{53} erg. We describe a scenario of burning of a NS into a hot, differentially rotating QS. Emission of released non-baryonic energy through the QS surface is discussed. The role of magnetobuoyancy of SQM is mentioned. The outflow of gamma e+ e- lasting for up to ~1000 s could be at the origin of long GRBs. Advantages of hot, differentially rotating QS as an inner engine of long GRBs are reviewed.
description: To be published in the proceedings of the conference "SWIFT and GRBs: Unveiling the Relativistic Universe", Venice, June 5-9, 2006. To appear in "Il Nuovo Cimento"
Unified Multipole Bott Indices for Non-Hermitian Skin Effect in Different Orders
Creators: name: Yang, Wuping
name: Huang, H.
Publisher: name: arXiv
Year: 2025
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Non-Hermitian systems exhibit a distinctive phenomenon known as the non-Hermitian skin effect, where an extensive number of eigenstates become localized at the boundaries of a lattice with open boundaries. While the spectral winding number under periodic boundary conditions is a well-established topological indicator for predicting the skin effect in one-dimensional non-Hermitian systems, a suitable topological invariant to diagnose higher-order skin effects remains elusive. In this Letter, we propose a unified non-Hermitian multipole characterization framework that generalizes the concept of spectral winding to higher-order skin effects. Specifically, we develop a set of non-Hermitian multipole Bott indices capable of diagnosing skin effects of different orders. Our approach provides a comprehensive understanding of both first- and higher-order skin effects in non-Hermitian systems, offering new perspectives for exploring topological phenomena in non-Hermitian systems.
description: published in Phys. Rev. B 111, 155121 (2025)
Rotating quantum liquids crystallize
Creators: name: Reimann, S. M.
name: Koskinen, M.
name: Yu, Y.
name: Manninen, M.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Small crystallites form when finite quantal systems are set highly rotating. This crystallization is independent of the statistics of the particles, and occurs for both trapped bosons and fermions. The spin degree of freedom does not change the tendency for localization. In a highly rotating state, the strongly correlated bosonic and fermionic systems approach to that of classical particles.
description: 14 pages 6 figures
Graduate recital
Creators: name: Kovarik, Christopher Matthew
Publisher: name: University of British Columbia
Year: 2009

description: The scores here collected represent all the music heard in the recital of 3 April, 1995 (programme on p. iii), save "Shimmering Reflections on a Dark Carrall Street Night." This is an electroacoustic piece which does, however, appear on the accompanying recording.
Provenance-Based Assessment of Plans in Context
Creators: name: Friedman, Scott E.
name: Goldman, Robert P.
name: Freedman, Richard G.
name: Kuter, Ugur
name: Geib, Christopher
name: Rye, Jeffrey
Publisher: name: arXiv
Year: 2020
Subjects: subject: Artificial Intelligence (cs.AI)
subject: Human-Computer Interaction (cs.HC)
subject: FOS: Computer and information sciences

description: Many real-world planning domains involve diverse information sources, external entities, and variable-reliability agents, all of which may impact the confidence, risk, and sensitivity of plans. Humans reviewing a plan may lack context about these factors; however, this information is available during the domain generation, which means it can also be interwoven into the planner and its resulting plans. This paper presents a provenance-based approach to explaining automated plans. Our approach (1) extends the SHOP3 HTN planner to generate dependency information, (2) transforms the dependency information into an established PROV-O representation, and (3) uses graph propagation and TMS-inspired algorithms to support dynamic and counter-factual assessment of information flow, confidence, and support. We qualified our approach's explanatory scope with respect to explanation targets from the automated planning literature and the information analysis literature, and we demonstrate its ability to assess a plan's pertinence, sensitivity, risk, assumption support, diversity, and relative confidence.
description: 9 pages, 7 figures, including in Proceedings of the 2020 ICAPS Workshop on Explainable AI Planning (XAIP)
An unidentified Fermi source emitting radio bursts in the Galactic bulge
Creators: name: Anna-Thomas, Reshma
name: Burke-Spolaor, Sarah
name: Law, Casey J.
name: Schinzel, F. K.
name: Aggarwal, Kshitij
name: Bower, Geoffrey C.
name: Connor, Liam
name: Demorest, Paul B.
Publisher: name: arXiv
Year: 2024
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We report on the detection of radio bursts from the Galactic bulge using the real-time transient detection and localization system, realfast. The pulses were detected commensally on the Karl G. Jansky Very Large Array during a survey of unidentified Fermi $γ$-ray sources. The bursts were localized to subarcsecond precision using realfast fast-sampled imaging. Follow-up observations with the Green Bank Telescope detected additional bursts from the same source. The bursts do not exhibit periodicity in a search up to periods of 480 s, assuming a duty cycle of < 20%. The pulses are nearly 100% linearly polarized, showing circular polarization up to 12%, and exhibit variable scattering on timescales of months. The arcsecond-level realfast localization links the source confidently with the Fermi $γ$-ray source and places it nearby (though not coincident with) an XMM-Newton X-ray source. Based on the source's overall properties, we discuss various options for the nature of this object and propose that it could be a young pulsar, a magnetar, or a binary pulsar system.
The Extensive Substructure and Long Star-Forming Histories of Young Stellar Populations in the Solar Neighborhood
Creators: name: Kerr, Ronan
name: Rizzuto, Aaron
name: Kraus, Adam
Publisher: name: Zenodo
Year: 2021
Subjects: Young stars
Star clusters and associations

description: Young stellar associations hold a star formation record that can persist for millions of years, and their study can provide critical insight into the progression of star formation. To identify new nearby young stellar populations, we generate a comprehensive Bayesian framework for the identification of young stars, and use it to identify just over 30000 credible young star candidates within a sample from Gaia DR2. Applying the HDBSCAN clustering algorithm to this sample, we identify 27 top-level groups, nearly half of which have little to no presence in previous literature. Ten of these groups have visible substructure, including notable young associations such as Orion, Perseus, Taurus, and Sco-Cen. We provide a complete subclustering analysis on all groups with substructure, and in doing so identify patterns in age capable of significantly expanding our knowledge of star formation. These patterns include an apparent primordial star formation origin for Sco-Cen along a semicircular arc, as well as clear evidence for sequential star formation moving away from that arc, with a star formation propagation speed of ~ 4 km/s We also identify earlier bursts of star formation in Perseus and Taurus that predate current, kinematically identical active star-forming events, suggesting that the mechanisms that collect gas can spark a second star-forming event after any initial gas dispersal. This paper represents the first in a series on these young populations, through which we hope to significantly expand our knowledge of the processes that guide star formation in nearby populations.
description: {"references": ["McInnes, L., Healy, J., & Astels, S. 2017, The Journal of Open Source Software", "Lallement, R., Babusiaux, C., Vergely, J. L., et al. 2019,A&A, 625, A135", "Gaia Collaboration, Brown, A. G. A., Vallenari, A., et al.2018, A&A, 616, A1"]}
The new pre-cataclysmic binary PG 2200+085
Creators: name: Shimansky, V.
name: Sakhibullin, N. A.
name: Bikmaev, I.
name: Ritter, H.
name: Suleimanov, V.
name: Borisov, N.
name: Galeev, A.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present the results of spectroscopic-- and orbit--sampled photometric observations of the faint UV-excess object PG 2200+085. The optical CCD photometry observations of this object were performed by the Russian-Turkish 1.5-meter telescope RTT150 at the TUBITAK National Observatory (Turkey). The long-slit optical spectroscopy observations with 2.6 A resolution were carried out by 6-meter telescope BTA at the Special Astrophysical Observatory (Russia). The photometric variations over two nights are almost sinusoidal with an amplitude Δm_V = 0.04 m and a period of P = 0.3186 d. Such a light curve is typical of a detached close binary with an illumination effect or the ellipsoidal deformation of a secondary star. The observed spectrum clearly displays a featureless blue continuum of a hot component and a rich absorption--line and molecular band K--star spectrum. The CaII line profiles with strong emission cores are remarkably similar to those of V471 Tau. We tentatively classify PG 2200+085 as a pre-cataclysmic binary of the V471 Tau type.
description: 8 pages, 5 figures, accepted for publication in A&A
Genuine entanglement detection via projection map in multipartite systems
Creators: name: Mallick, Bivas
name: Nandi, Sumit
Publisher: name: arXiv
Year: 2024
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We present a formalism to detect genuine multipartite entanglement by considering projection map which is a positive but not completely positive map. Projection map has been motivated by the no-pancake theorem which repudiates the existence of a quantum operation that maps the Bloch sphere onto a disk along its equator. The not complete positivity feature of projection map is explored to investigate genuine multipartite entanglement in arbitrary N-qubit quantum systems. Our proposed framework can detect some important classes of genuinely entangled states in tripartite and quadripartite scenarios. We provide illustrative example to show the efficacy of our formalism to detect a class of tripartite PPT bound entangled states. Finally, we construct a suitable witness operator based on projection map to certify genuine tripartite entanglement, which is likely to be feasible experimentally.
description: 11 pages, 5 figures, Close to published version
Paranemoura perfecta
Creators: name: Grubbs, Scott A.
name: Pessino, Massimo
name: DeWalt, R. Edward
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Plecoptera
Nemouridae
Paranemoura
Paranemoura perfecta

description: Paranemoura perfecta (Walker) Collection records. USA, Michigan: Alger Co., spring into Lake Superior, along North Country National Scenic Trail, Pictured Rocks National Lakeshore, 46.5528, -86.4241, 21. V.2009, S.A Grubbs, 5♂, 10♀ (WKU). Marquette Co., T47 N, R23 W, S24, Tributary Sand River, 46.4599, -87.1187, 10. V.1980, M. Arduser, 2♂, 16♀ (MSUC). Comments. Similar to O. albidipennis, this is an Appalachian species reported mainly from Atlantic Canada south to eastern Tennessee (Baumann 1996, DeWalt et al. 2012a). Focused collecting efforts in forested upland streams should also reveal additional populations of this species.
description: Published as part of Grubbs, Scott A., Pessino, Massimo & DeWalt, R. Edward, 2012, Michigan Plecoptera (Stoneflies): Distribution Patterns And An Updated Species List, pp. 162-173 in Illiesia 8 (18) on page 169, DOI: 10.5281/zenodo.4753235
description: {"references": ["Baumann, R. W. 1996. A review of the stonefly genus Paranemoura (Plecoptera: Nemouridae) and a new species from the northeast. Proceedings of the Entomological Society of Washington, 98: 818 - 826."]}