cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Scroll-wave dynamics in the presence of ionic and conduction inhomogeneities in an anatomically realistic mathematical model for the pig heart
Creators: name: Majumder, R.
name: Pandit, R
name: Panfilov, A. V.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Biological Physics (physics.bio-ph)
subject: Tissues and Organs (q-bio.TO)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: Nonlinear waves of the reaction-diffusion (RD) type occur in many biophysical systems, including the heart, where they initiate cardiac contraction. Such waves can form vortices called scroll waves, which result in the onset of life-threatening cardiac arrhythmias. The dynamics of scroll waves is affected by the presence of inhomogeneities, which, in a very general way, can be of \textit{(i)} ionic type, i.e., they affect the reaction part, or \textit{(ii)} conduction type, i.e., they affect the diffusion part of an RD equation. We demostrate, for the first time, by using a state-of-the-art, anatomically realistic model of the pig heart, how differences in the geometrical and biophysical nature of such inhomogeneities can influence scroll-wave dynamics in different ways. Our study reveals that conduction-type inhomogeneities become increasingly important at small length scales, i.e., in the case of multiple, randomly distributed, obstacles in space at the cellular scale ($0.2-0.4{\rm mm}$). Such configurations can lead to scroll-wave break up. In contrast, ionic inhomogeneities, affect scroll-wave dynamics significantly at large length scales, when these inhomogeneities are localized in space at the tissue level ($5-10$ mm). In such configurations, these inhomogeneities can (a) attract scroll waves, by pinning them to the heterogeneity, or (b) lead to scroll-wave breakup.
Energy backflow in unidirectional spatiotemporally localized wavepackets
Creators: name: Besieris, Ioannis
name: Saari, Peeter
Publisher: name: arXiv
Year: 2022
Subjects: subject: Optics (physics.optics)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Backflow, or retro-propagation, is a counterintuitive phenomenon where for a forward-propagating wave the energy or probability density locally propagates backward. In this study the energy backflow has been examined in connection with relatively simple causal unidirectional finite-energy solutions of the wave equation which are derived from a factorization of the so-called basic splash mode. Specific results are given for the energy backflow arising in known azimuthally symmetric unidirectional wavepackets, as well as in novel azimuthally asymmetric extensions. Using the Bateman-Whittaker technique, a novel finite-energy unidirectional null localized wave has been constructed that is devoid of energy backflow and has some of the topological properties of the basic Hopfion.
description: 10 pages, 8 figures. In comparison with v1, some refs. to arXiv have been updated by journal ones, some paragraphs in Introduction revised and a remark about possible experimental verification added to Conclusions
Search reliability and search efficiency of combined Lévy-Brownian motion: long relocations mingled with thorough local exploration
Creators: name: Palyulin, V. V.
name: Chechkin, A. V.
name: Klages, R.
name: Metzler, R.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Populations and Evolution (q-bio.PE)
subject: Quantitative Methods (q-bio.QM)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: A combined dynamics consisting of Brownian motion and Lévy flights is exhibited by a variety of biological systems performing search processes. Assessing the search reliability of ever locating the target and the search efficiency of doing so economically of such dynamics thus poses an important problem. Here we model this dynamics by a one-dimensional fractional Fokker-Planck equation combining unbiased Brownian motion and Lévy flights. By solving this equation both analytically and numerically we show that the superposition of recurrent Brownian motion and Lévy flights with stable exponent $α<1$, by itself implying zero probability of hitting a point on a line, lead to transient motion with finite probability of hitting any point on the line. We present results for the exact dependence of the values of both the search reliability and the search efficiency on the distance between the starting and target positions as well as the choice of the scaling exponent $α$ of the Lévy flight component.
description: 22 pages, 6 figures
Constraints on hadron resonance gas interactions via first-principles Lattice QCD susceptibilities
Creators: name: Karthein, Jamie M.
name: Koch, Volker
name: Ratti, Claudia
name: Vovchenko, Volodymyr
Publisher: name: arXiv
Year: 2022
Subjects: subject: Nuclear Theory (nucl-th)
subject: High Energy Physics - Lattice (hep-lat)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We investigate extensions of the Hadron Resonance Gas (HRG) Model beyond the ideal case by incorporating both attractive and repulsive interactions into the model. When considering additional states exceeding those measured with high confidence by the Particle Data Group, attractive corrections to the overall pressure in the HRG model are imposed. On the other hand, we also apply excluded-volume corrections, which ensure there is no overlap of baryons by turning on repulsive (anti)baryon-(anti)baryon interactions. We emphasize the complementary nature of these two extensions and identify combinations of conserved charge susceptibilities that allow us to constrain them separately. In particular, we find interesting ratios of susceptibilities that are sensitive to one correction and not the other. This allows us to constrain the excluded volume and particle spectrum effects separately. Analysis of the available lattice results suggests the presence of both the extra states in the baryon-strangeness sector and the repulsive baryonic interaction, with indications that hyperons have a smaller repulsive core than non-strange baryons. We note that these results are interesting for heavy-ion-collision systems at both the LHC and RHIC.
description: Contribution to the 20th International Conference on Strangeness in Quark Matter (SQM2022)
Reconnection-Driven Magnetohydrodynamic Turbulence in a Simulated Coronal-Hole Jet
Creators: name: Uritsky, Vadim M.
name: Roberts, Merrill A.
name: DeVore, C. Richard
name: Karpen, Judith T.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Extreme-ultraviolet and X-ray jets occur frequently in magnetically open coronal holes on the Sun, especially at high solar latitudes. Some of these jets are observed by white-light coronagraphs as they propagate through the outer corona toward the inner heliosphere, and it has been proposed that they give rise to microstreams and torsional Alfvén waves detected in situ in the solar wind. To predict and understand the signatures of coronal-hole jets, we have performed a detailed statistical analysis of such a jet simulated with an adaptively refined magnetohydrodynamics model. The results confirm the generation and persistence of three-dimensional, reconnectiondriven magnetic turbulence in the simulation. We calculate the spatial correlations of magnetic fluctuations within the jet and find that they agree best with the Müller - Biskamp scaling model including intermittent current sheets of various sizes coupled via hydrodynamic turbulent cascade. The anisotropy of the magnetic fluctuations and the spatial orientation of the current sheets are consistent with an ensemble of nonlinear Alfvén waves. These properties also reflect the overall collimated jet structure imposed by the geometry of the reconnecting magnetic field. A comparison with Ulysses observations shows that turbulence in the jet wake is in quantitative agreement with that in the fast solar wind.
description: 26 pages, 13 figures, 1 table
Young Stars with SALT
Creators: name: Riedel, Adric R.
name: Alam, Munazza K.
name: Rice, Emily L.
name: Cruz, Kelle L.
name: Henry, Todd J.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We present a spectroscopic and kinematic analysis of 79 nearby M dwarfs in 77 systems. All are low-proper-motion southern hemisphere objects and were identified in a nearby star survey with a demonstrated sensitivity to young stars. Using low-resolution optical spectroscopy from the Red Side Spectrograph (RSS) on the South African Large Telescope (SALT), we have determined radial velocities, H-alpha, Lithium 6708Å, and Potassium 7699Å~equivalent widths linked to age and activity, and spectral types for all our targets. Combined with astrometric information from literature sources, we identify 44 young stars. Eighteen are previously known members of moving groups within 100 parsecs of the Sun. Twelve are new members, including one member of the TW Hydra moving group, one member of the 32 Orionis moving group, nine members of Tucana-Horologium, one member of Argus, and two new members of AB Doradus. We also find fourteen young star systems that are not members of any known groups. The remaining 33 star systems do not appear to be young. This appears to be evidence of a new population of nearby young stars not related to the known nearby young moving groups.
description: 23 pages, 11 figures, 6 tables. Accepted to ApJ
All passive photonic power divider with arbitrary split ratio
Creators: name: Xu, Ke
name: Liu, Lu
name: Wen, Xiang
name: Sun, Wenzhao
name: Zhang, Nan
name: Yi, Ningbo
name: Sun, Shang
name: Xiao, Shumin
name: Song, Qinghai
Publisher: name: arXiv
Year: 2016
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Integrated optical power splitter is one of the fundamental building blocks in photonic integrated circuits (PIC). Conventional multimode interferometer based power splitter is widely used as it has reasonable footprint and is easy to fabricate. However, it is challenging to realize arbitrary split ratio especially for multi-outputs. In this work, an ultra-compact power splitter with a QR code-like nanostructure is designed by a nonlinear fast search method (FSM). The highly functional structure is composed of a number of freely designed square pixels with the size of 120nm x 120nm which could be either dielectric or air. The lightwaves are scattered by a number of etched squares with optimized locations and the scattered waves superimpose at the outputs with the desired power ratio. We demonstrate 1x2 splitters with 1:1, 1:2, 1:3 split ratios and a 1x3 splitter with the ratio of 1:2:1. The footprint for all the devices is only 3.6umx3.6 um. Well-controlled split ratios are measured for all the cases. The measured transmission efficiencies of all the splitters are close to 80% over 30 nm wavelength range.
Impact of built-in fields and contact configuration on the characteristics of ultra-thin GaAs solar cells
Creators: name: Aeberhard, Urs
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We discuss the effects of built-in fields and contact configuration on the photovoltaic characteristics of ultrathin GaAs solar cells. The investigation is based on advanced quantum-kinetic simulations reaching beyond the standard semi-classical bulk picture concerning the consideration of charge carrier states and dynamics in complex potential profiles. The thickness dependence of dark and photocurrent in the ultra-scaled regime is related to the corresponding variation of both, the built-in electric fields and associated modification of the density of states, and the optical intensity in the films. Losses in open-circuit voltage and short-circuit current due to leakage of electronically and optically injected carriers at minority carrier contacts are investigated for different contact configurations including electron and hole blocking barrier layers. The microscopic picture of leakage currents is connected to the effect of finite surface recombination velocities in the semi-classical description, and the impact of these non-classical contact regions on carrier generation and extraction is analyzed.
description: 5 pages, 8 figures
Proper Motion of the Leo II Dwarf Galaxy Based On Hubble Space Telescope Imaging
Creators: name: Piatek, Slawomir
name: Pryor, Carlton
name: Olszewski, Edward W.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: This article reports a measurement of the proper motion of Leo II, a dwarf galaxy that is a likely satellite of the Milky Way, based on imaging with the Hubble Space Telescope and Wide Field Camera 3. The measurement uses compact background galaxies as standards of rest in both channels of the camera for two distinct pointings of the telescope and a QSO in one channel for each pointing, resulting in the weighted average of six measurements. The measured proper motion in the the equatorial coordinate system is (mu_alpha, mu_delta) = (-6.9 +- 3.7, -8.7 +- 3.9) mas/century and in the Galactic coordinate system is (mu_l, mu_b) = (6.2 +- 3.9, -9.2 +- 3.7) mas/century. The implied space velocity with respect to the Galactic center is (Pi, Theta, Z) = (-37 +- 38, 117 +- 43, 40 +- 16) km/s or, expressed in Galactocentric radial and tangential components, (V_r, V_tan) = (21.9 +- 1.5, 127 +- 42) km/s. The space velocity implies that the instantaneous orbital inclination is 68 degrees, with a 95% confidence interval of (66 deg, 80 deg). The measured motion supports the hypothesis that Leo II, Leo IV, Leo V, Crater 2, and the globular cluster Crater fell into the Milky Way as a group.
description: 19 pages, 19 figures, 4 tables; submitted to the Astronomical Journal
Model-Independent Test for Gravity using Intensity Mapping and Galaxy Clustering
Creators: name: Abidi, Muntazir M.
name: Bonvin, Camille
name: Jalilvand, Mona
name: Kunz, Martin
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We propose a novel method to measure the $E_G$ statistic from clustering alone. The $E_G$ statistic provides an elegant way of testing the consistency of General Relativity by comparing the geometry of the Universe, probed through gravitational lensing, with the motion of galaxies in that geometry. Current $E_G$ estimators combine galaxy clustering with gravitational lensing, measured either from cosmic shear or from CMB lensing. In this paper, we construct a novel estimator for $E_G$, using only clustering information obtained from two tracers of the large-scale structure: intensity mapping and galaxy clustering. In this estimator, both the velocity of galaxies and gravitational lensing are measured through their impact on clustering. We show that with this estimator, we can suppress the contaminations that affect other $E_G$ estimators and consequently test the validity of General Relativity robustly. We forecast that with the coming generation of surveys like HIRAX and Euclid, we will measure $E_G$ with a precision of up to 7% (3.9% for the more futuristic SKA2).
description: 14 pages, 6 figures; v3: version matching published one
title: Realism, Speculative Realism, and Transgressive Realism
titleType: Other
Creators: name: Akyol, Umit
Publisher: name: University of Dundee
Year: 2023

description: In this thesis, I discuss the issue of realism with regard to Quentin Meillassoux’s Speculative Realism and Lee Braver’s Transgressive Realism. I aim to find out whether and how these two continental realist projects legitimately resolve the issue.

In the first chapter, I outline the realism issue in detail, with historical and systematic analyses. In the systematic section, I propose two distinctions: realism as an ontological thesis (R ont) and realism as an epistemological thesis (R epis). R ont is the thesis that there is a reality existing independently of us, while R epis is the thesis that we can access this reality. I conclude the systematic analysis with the claim that there is an enigmatic relation between R ont and R epis, in which the problem of realism has it source. In the historical analysis, I focus on René Descartes since his main philosophical project is one of the most important modern philosophical sources for continental realism. His project promises to legitimize R ont and R epis. However, I conclude that Descartes fails to justify this aim, and this failure is turned into a legacy, namely the Cartesian Legacy, having a profound effect on the question of realism in contemporary continental philosophy.

In the second chapter, Meillassoux promises to legitimize R ont and R epis in his speculative realist project. This project consists of two fundamental claims: 1) being is independent of thought (us) (R ont) and 2) we can have access to being as it is independent of thought (R epis). However, I argue that Meillassoux fails to fulfil his promise because his project collapses the border between R ont and R epis by dissolving the former into the latter.

In the third chapter, I discuss Lee Braver’s Transgressive Realism and argue his project provides us with a meaningful realist stance that can successfully account for the enigmatic relation between R ont and R epis. I first outline his historical reading of transgressive realism, which consists of three steps, with each step correlated to a thinker: Kant, Hegel, and Kierkegaard. I then examine the Heideggerian form of Transgressive Realism. Finally, I compare Braver’s Transgressive Realism with Meillassoux’s Speculative Realism and I conclude that the former project is more effective than the latter project at solving the problem of realism.
Grüss type inequalities for positive linear maps on $C^*$-algebras
Creators: name: Dadkhah, Ali
name: Moslehian, Mohammad Sal
Publisher: name: arXiv
Year: 2016
Subjects: subject: Operator Algebras (math.OA)
subject: Functional Analysis (math.FA)
subject: FOS: Mathematics
subject: 47A63, 47A30, 46L08, 15A60

description: Let $\mathcal{A}$ and $\mathcal{B}$ be two unital $C^*$-algebras and let for $C\in\mathcal{A},\ Γ_C=\{γ\in \mathbb{C} : \|C-γI\|=\inf_{α\in \mathbb{C}} \|C-αI\|\}$. We prove that if $Φ:\mathcal{A} \longrightarrow \mathcal{B}$ is a unital positive linear map, then \begin{eqnarray*} \big|Φ(AB)-Φ(A)Φ(B)\big| \leq \big\|Φ(|A^*-ζI|^2)\big\|^\frac{1}{2} \big[Φ(|B-ξI|^2)\big]^\frac{1}{2} \end{eqnarray*} for all $A,B\in\mathcal{A}, ζ\in Γ_A$ and $ξ\inΓ_B.$\\ In addition, we show that if $(\mathcal{A},τ)$ is a noncommutative probability space and $T \in \mathcal{A}$ is a density operator, then \begin{eqnarray*} \ \ \big|τ(TAB)-τ(TA)τ(TB)\big|\leq \|A-ζI\|_p\|B-ξI\|_q\|T\|_r \ \ (p,q\geq 4, r\geq 2) \end{eqnarray*} and \begin{eqnarray*} \big|τ(TAB)-τ(TA)τ(TB)\big|\leq \|A-ζI\|_p\|B-ξI\|_q\|T\| \ \ \ \ (p,q\geq 2)\ \ \ \ \ \end{eqnarray*} for every $A,B \in \mathcal{A}$ and $ζ\in Γ_A,ξ\in Γ_B$. Our results generalize the corresponding results for matrices to operators on spaces of arbitrary dimension.
description: 15 pages; to appear in Linear Multilinear Algebra
Oceanic dipoles in a surface quasigeostrophic model
Creators: name: Johnson, E. R.
name: Crowe, M. N.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Atmospheric and Oceanic Physics (physics.ao-ph)
subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: Analysis of satellite altimetry and Argo float data leads Ni et al. (2020, JGR Oceans) to argue that mesoscale dipoles are widespread features of the global ocean having a relatively uniform three-dimensional structure that can lead to strong vertical exchanges. Almost all the features of the composite dipole they construct can be derived from a model for multipoles in the surface quasigeostrophic equations for which we present a straightforward novel solution in terms of an explicit linear eigenvalue problem, allowing simple evaluation of the higher radial modes that appear to be present in the observations and suggesting that mass conservation may explain the observed frontogenetic velocities.
KOS-based Enrichment of Archaeological Fieldwork Reports
Creators: name: Tudhope, Douglas
name: Binding, Ceri
Publisher: name: Zenodo
Year: 2023
Subjects: Named Entity Recognition, NIR, automatic indexing, archeology, Knowledge Organization System, KOS
NIR
Automatic indexing
Archeology
Knoweldege Organization System
KOS

description: Semantic enrichment techniques and tools based on knowledge organization systems (KOS) have an important role to play in supporting information discovery. This paper reports on initial work investigating and developing KOS-based automatic indexing recommendation tools (for final intellectual judgment) in the archaeology domain. Within the UK, the OASIS online index of fieldwork events and their unpublished reports has been a major initiative to make archaeological fieldwork available to a wider public. OASIS is hosted by the Archaeology Data Service and is supported by Historic England and Historic Environment Scotland. OASIS reports are contributed by a wide variety of organisations and subject indexing is inconsistent and sometimes sparse, although use of standard KOS from the Forum on Information Standards in Heritage is encouraged. Initial results from a pilot case study for an automatic (KOS-based) subject indexing recommendation system are reported. Findings include the need for some pre-processing of the KOS vocabularies for NLP purposes and the need for post-processing filters to prioritise subject indexing significant for the document in question. The paper goes on to reflect on evaluation issues for such systems and to make some general comparisons with automatic indexing for Name Authorities and Named Entity Recognition.
Unveiling the AI Quandary: Harnessing AI for Societal Advancement
Creators: name: Adewumi, Abayomi-Alli Adebayo
Publisher: name: Zenodo
Year: 2023
Subjects: Artificial intelligence

description: On Wednesday September 13, 2023, I presented the lead paper at the 2023 edition of the FUNAAB College of Physical Sciences Student Association (COLPHYSSA) annual symposium. The paper was titled "Unveiling the AI Quandary and Harnessing it for Societal Advancement”. Here are the highlights of the paper. Artificial Intelligence (AI) is revolutionizing our world, impacting various aspects of society, and offering tremendous potential for advancements. From healthcare to finance, transportation to education, AI is transforming industries, driving innovation, and shaping our future. We talked on the societal benefits of AI such as: Improved healthcare outcomes personalised services automation of mundane tasks enhanced decision making. Important ethical considerations in AI development and deployment were also mentioned, such as: Privacy concerns and the need safeguarding our personal information. Ensuring fairness and equity to prevent Algorithmic bias. Need for upskilling and workforce retraining to avoid job displacement. Bridging the digital divide for inclusive AI adoption. Some concerns with narrow AI getting out of control was discussed. How much of our privacy are we willing to give up? Over 400M CCTV in China, US and others. Social credit in China, etc. We are gradually ceding our autonomy as humans to AI as in autonomous weapons, auto control drones, self-driving cars, transhumanism (enhance humans), etc. We mentioned some of the potential dangers associated with the development and deployment of Artificial General Intelligence (AGI) despite its potential for positive impact. The potential dangers include: Superintelligence Unintended Consequences Lack Of Control Job Disruption Security Risks Value Misalignment Rapid Development Race Ethical Considerations. As students some ethical considerations for the use of AI were highlighted as: Cheating using AI, Unethical Data gathering, Bias and discrimination, Unauthorised AI experimentation and social manipulation. I admonished that AI should be used responsibly as students, so we must understand the implications of AI usage, ensure ethical data use, avoid bias and discrimination, ensure AI solutions are transparent and explainable, respect intellectual property rights, engage in responsible innovation, promote accountability and responsibility. The need for Transparency, fairness, accountability and privacy in AI Development was mentioned. There is need for a combination of human expertise and AI capabilities so that humans and AI systems can complement each other’s strengths. To address the AI quandaries, we discussed the need for interdisciplinary collaboration, appropriate policy frameworks and public engagements. The presentation concluded that by harnessing the power of AI while considering its ethical implications, we can unlock its full potential to create positive social impact, drive innovation, and address complex challenges.
Ordinal analysis of lexical patterns
Creators: name: Sanchez, David
name: Zunino, Luciano
name: De Gregorio, Juan
name: Toral, Raul
name: Mirasso, Claudio
Publisher: name: arXiv
Year: 2022
Subjects: subject: Computation and Language (cs.CL)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Physics and Society (physics.soc-ph)
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences

description: Words are fundamental linguistic units that connect thoughts and things through meaning. However, words do not appear independently in a text sequence. The existence of syntactic rules induces correlations among neighboring words. Using an ordinal pattern approach, we present an analysis of lexical statistical connections for 11 major languages. We find that the diverse manners that languages utilize to express word relations give rise to unique pattern structural distributions. Furthermore, fluctuations of these pattern distributions for a given language can allow us to determine both the historical period when the text was written and its author. Taken together, our results emphasize the relevance of ordinal time series analysis in linguistic typology, historical linguistics and stylometry.
description: 9 pages, 12 figures, 2 tables; v2: the section on universality has been removed because previous results were affected by spurious correlations. Published version
A multi-criteria decision making model for dredger dispatching under uncertainty
Creators: name: Pan, Hongqi.
Publisher: name: Monash University
Year: 2022

description: This thesis was scanned from the print manuscript for digital preservation and is copyright the author.
 Researchers can access this thesis by asking their local university, institution or public library to
 make a request on their behalf. Monash staff and postgraduate students can use the link in the References field.
Quadrature-based Lattice Boltzmann Model for Relativistic Flows
Creators: name: Blaga, Robert
name: Ambrus, Victor E.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: A quadrature-based finite-difference lattice Boltzmann model is developed that is suitable for simulating relativistic flows of massless particles. We briefly review the relativistc Boltzmann equation and present our model. The quadrature is constructed such that the stress-energy tensor is obtained as a second order moment of the distribution function. The results obtained with our model are presented for a particular instance of the Riemann problem (the Sod shock tube). We show that the model is able to accurately capture the behavior across the whole domain of relaxation times, from the hydrodynamic to the ballistic regime. The property of the model of being extendable to arbitrarily high orders is shown to be paramount for the recovery of the analytical result in the ballistic regime.
description: 6 pages, 2 figures, proceedings of TIM 15-16 conference (26-28 May 2016, Timisoara, Romania)
Ising and Gross-Neveu model in next-to-leading order
Creators: name: Knorr, Benjamin
Publisher: name: arXiv
Year: 2016
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We study scalar and chiral fermionic models in next-to-leading order with the help of the functional renormalisation group. Their critical behaviour is of special interest in condensed matter systems, in particular graphene. To derive the beta functions, we make extensive use of computer algebra. The resulting flow equations were solved with pseudo-spectral methods to guarantee high accuracy. New estimates on critical quantities for both the Ising and the Gross-Neveu model are provided. For the Ising model, the estimates agree with earlier renormalisation group studies of the same level of approximation. By contrast, the approximation for the Gross-Neveu model retains many more operators than all earlier studies. For two Dirac fermions, the results agree with both lattice and large-$N_f$ calculations, but for a single flavour, different methods disagree quantitatively, and further studies are necessary.
description: 11 pages, 5 figures, 1 ancillary Mathematica notebook
Level dynamics and avoided level crossings in driven disordered quantum dots
Creators: name: Grabarits, András
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: The statistical properties of the dynamics of energy levels are investigated in the case of two two-dimensional disordered quantum dot models with nearest neighbor hopping subjected to external time-dependent perturbations. While in the first model the external drivings are realized by a continuous variation of the on-site energies, in the second one it is generated by deformations of a parabolic potential. We concentrate on the effects of the potential on the localization properties and investigate the statistics of the energy level velocities and curvatures regarding their typical magnitudes and domain of agreement with the predictions of Random Matrix Theory (RMT) for the Gaussian Orthogonal, Unitary and Symplectic ensembles. Moreover, the statistical properties of the avoided level crossings are investigated in terms of the corresponding Landau-Zener parameters. We find that the strength of the Landau-Zener transitions exhibits universal behavior which also implies universal single-particle dynamics for slow perturbations independent of the disorder and potential strength, the system size and the symmetry class. These results can be verified experimentally by measurements of single-particle energy spectra in quantum dots.
description: 11 pages, 6 figures
Tailoring Nanowire Lasing Modes via Coupling to Metal Gratings
Creators: name: Vitale, Francesco
name: Repp, Daniel
name: Siefke, Thomas
name: Zeitner, Uwe
name: Peschel, Ulf
name: Pertsch, Thomas
name: Ronning, Carsten
Publisher: name: arXiv
Year: 2022
Subjects: subject: Optics (physics.optics)
subject: Applied Physics (physics.app-ph)
subject: FOS: Physical sciences

description: Tailoring the emission of plasmonic nanowire-based lasers represents one of the major challenges in the field of nanoplasmonics, given the envisaged integration of such devices into on-chip all-optical circuits. In this study, we proposed a mode selection scheme based on distributed feedback, achieved via the external coupling of single zinc oxide nanowires to an aluminum grating, which enabled a quasi-single mode lasing action. The nano-manipulation of a single nanowire allowed for a reliable comparison of the lasing emission characteristics in both planar (i.e. nanowire on the metallic substrate) and on-grating configurations. We found that, by varying the orientation of the nanowire on the grating, only when the nano-cavity was perpendicular to the ridge direction, an additional peak emerged in the emission spectrum on the low-energy side of the gain envelope. As a consequence of the fulfillment of the Bragg condition, such a peak was attributed to a hybrid mode dominating the mode competition. Simulation results showed that the hybrid mode could be efficiently waveguided along the nanowire cavity and supported by localized plasmon polaritons building up at the raised features ("fences") on top of the metal grating ridges. Moreover, the hybrid mode was found to experience an extra reflectance of nearly 50% across the grating periods, in addition to that provided by the nanowire end facets.
An intrinsic volume metric for the class of convex bodies in $\mathbb{R}^n$
Creators: name: Besau, Florian
name: Hoehner, Steven
Publisher: name: arXiv
Year: 2022
Subjects: subject: Metric Geometry (math.MG)
subject: Probability (math.PR)
subject: FOS: Mathematics
subject: 52A20, 52A22, 52A27 (Primary) 52A39, 52B11 (Secondary)

description: A new intrinsic volume metric is introduced for the class of convex bodies in $\mathbb{R}^n$. As an application, an inequality is proved for the asymptotic best approximation of the Euclidean unit ball by arbitrarily positioned polytopes with a restricted number of vertices under this metric. This result improves the best known estimate, and shows that dropping the restriction that the polytope is contained in the ball or vice versa improves the estimate by at least a factor of dimension. The same phenomenon has already been observed in the special cases of volume, surface area and mean width approximation of the ball.
description: 27 pages (revision: expanded Section 2, shorter proof of Thm. 4.2). To appear in Communications in Contemporary Mathematics
Unitarily invariant norm inequalities for elementary operators involving $G_{1}$ operators
Creators: name: Kittaneh, Fuad
name: Moslehian, Mohammad Sal
name: Sababheh, Mohammad
Publisher: name: arXiv
Year: 2016
Subjects: subject: Functional Analysis (math.FA)
subject: Operator Algebras (math.OA)
subject: FOS: Mathematics
subject: 15A60, 30E20, 47A30, 47B10, 47B15, 47B20

description: In this paper, motivated by perturbation theory of operators, we present some upper bounds for $|||f(A)Xg(B)+ X|||$ in terms of $|||\,|AXB|+|X|\,|||$ and $|||f(A)Xg(B)- X|||$ in terms of $|||\,|AX|+|XB|\,|||$, where $A, B$ are $G_{1}$ operators, $|||\cdot|||$ is a unitarily invariant norm and $f, g$ are certain analytic functions. Further, we find some new upper bounds for the the Schatten $2$-norm of $f(A)X\pm Xg(B)$. Several special cases are discussed as well.
description: 11 pages; to appear in Linear Algebra Appl. (LAA)
Faint Object Detection in Multi-Epoch Observations via Catalog Data Fusion
Creators: name: Budavari, Tamas
name: Szalay, Alexander S.
name: Loredo, Thomas J.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: Observational astronomy in the time-domain era faces several new challenges. One of them is the efficient use of observations obtained at multiple epochs. The work presented here addresses faint object detection with multi-epoch data, and describes an incremental strategy for separating real objects from artifacts in ongoing surveys, in situations where the single-epoch data are summaries of the full image data, such as single-epoch catalogs of flux and direction estimates for candidate sources. The basic idea is to produce low-threshold single-epoch catalogs, and use a probabilistic approach to accumulate catalog information across epochs; this is in contrast to more conventional strategies based on co-added or stacked image data across all epochs. We adopt a Bayesian approach, addressing object detection by calculating the marginal likelihoods for hypotheses asserting there is no object, or one object, in a small image patch containing at most one cataloged source at each epoch. The object-present hypothesis interprets the sources in a patch at different epochs as arising from a genuine object; the no-object (noise) hypothesis interprets candidate sources as spurious, arising from noise peaks. We study the detection probability for constant-flux objects in a simplified Gaussian noise setting, comparing results based on single exposures and stacked exposures to results based on a series of single-epoch catalog summaries. Computing the detection probability based on catalog data amounts to generalized cross-matching: it is the product of a factor accounting for matching of the estimated fluxes of candidate sources, and a factor accounting for matching of their estimated directions. We find that probabilistic fusion of multi-epoch catalog information can detect sources with only modest sacrifice in sensitivity and selectivity compared to stacking.
description: 11 pages, 11 figures
Structural Transitions in Dense Networks
Creators: name: Lambiotte, R.
name: Krapivsky, P. L.
name: Bhat, U.
name: Redner, S.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We introduce an evolving network model in which a new node attaches to a randomly selected target node and also to each of its neighbors with probability $p$. The resulting network is sparse for $p
description: 5 pages, 5 figures, revtex 2-column format
Higher Gauge Theories from Lie n-algebras and Off-Shell Covariantization
Creators: name: Carow-Watamura, Ursula
name: Heller, Marc Andre
name: Ikeda, Noriaki
name: Kaneko, Yukio
name: Watamura, Satoshi
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We analyze higher gauge theories in various dimensions using a supergeometric method based on a differential graded symplectic manifold, called a QP-manifold, which is closely related to the BRST-BV formalism in gauge theories. Extensions of the Lie 2-algebra gauge structure are formulated within the Lie n-algebra induced by the QP-structure. We find that in 5 and 6 dimensions there are special extensions of the gauge algebra. In these cases, a restriction of the gauge symmetry by imposing constraints on the auxiliary gauge fields leads to a covariantized theory. As an example we show that we can obtain an off-shell covariantized higher gauge theory in 5 dimensions, which is similar to the one proposed in [1] (arxiv:1206.5643).
description: 39 pages
The axion flavour connection
Creators: name: Darmé, Luc
name: Nardi, Enrico
name: Smarra, Clemente
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: A local flavour symmetry acting on the quarks of the Standard Model can automatically give rise to an accidental global $U(1)$ which remains preserved from sources of explicit breaking up to a large operator dimension, while it gets spontaneously broken together with the flavour symmetry. Such non-fundamental symmetries are often endowed with a mixed QCD anomaly, so that the strong CP problem is automatically solved via the axion mechanism. We illustrate the general features required to realise this scenario, and we discuss a simple construction based on the flavour group $SU(3)\times SU(2) \times U(1)_F$ to illustrate how mass hierarchies can arise while ensuring at the same time a high quality Peccei-Quinn symmetry.
description: 11 pages, no figures
Disorder-sensitive pump-probe measurements on Nd$_{1.83}$Ce$_{0.17}$CuO$_{4\pmδ}$ films
Creators: name: Avella, Adolfo
name: Buonavolontà, Carmela
name: Guarino, Anita
name: Valentino, Massimo
name: Leo, Antonio
name: Grimaldi, Gaia
name: de Lisio, Corrado
name: Nigro, Angela
name: Pepe, Giampiero
Publisher: name: arXiv
Year: 2016
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We find an unambiguous relationship between disorder-driven features in the temperature dependence of the resistance and the behavior, as functions of the temperature, of the parameters necessary to describe some of the relaxation processes in the photoinduced differential time-resolved reflectivity of three samples of Nd$_{1.83}$Ce$_{0.17}$CuO$_{4\pmδ}$. The latter, sharing the same Ce content, have been fabricated and annealed ad-hoc in order to differ only for the degree of disorder, mainly related to oxygen content and location, and, consequently, for the temperature dependence of the resistance: two of them present a minimum in the resistance and behave as a superconductor and as a metal, respectively, the third behaves as an insulator. The systematic coherence between the resistance and the relaxation parameters behaviors in temperature for all three samples is absolutely remarkable and shows that pump-probe measurements can be extremely sensitive to disorder as it drives the emergence of new excitations and of the related relaxation channels as in this paradigmatic case.
description: 9 pages, 6 figures (17 panels)
A quantum for a quantum
Creators: name: Saugmann, Pil Maria
Publisher: name: Zenodo
Year: 2022

description: This thesis centers on how to use exotic lattices in different ways to design potential quantum simulators. These exotic lattices are either real physical objects in the form of ultra cold atoms in bipartite optical lattice systems or lattice models revealed in state space. For optical lattices, the potential wells forms a lattice, such that the atoms of the system will be highly localized at the potential minima, and where the bipartite nature of the lattice ensures that the lattice sites will alternate between two different types. When studying the atoms in the optical lattices they can be described by a Bose-Hubbard model, where it turns out that bipartite lattice systems provides a route to realizing frustration through competing nearest and next nearest neighbor couplings in both the superfluid phase and the Mott insulating phase.

 For state space lattices are no longer objects in real space, but instead they live in state space. Though such state space lattice models can be represented as single particle systems, they still hold a potential for realizing quantum simulators. For this type of exotic lattices, the focus is on how to study quantum optical models in terms of their Fock space lattices (FSLs). Such models only have a few degrees-of-freedom which together with symmetries of these system, make it simple to identify the emerging FSLs with know lattice models from the condensed matter. Thus shedding new light on the quantum optical systems at hand. The three-mode Jaynes-Cummings model in the large detuned limit, is used as an example to display the strength of this method. It is the growth of a systems state space, that determines whether the system is a potential quantum simulator or not. For a system to be a quantum simulator, the growth of the phase space has to be such, that it becomes computational hard to find the systems energy. This means, that if we can design a state space lattice, which grows exponential, then we have a potential candidate for a quantum simulator. The Bethe lattice is one such example that grows exponentially.
Intensity Limit in Compact H$^-$ and H$_2^+$ Cyclotrons
Creators: name: Planche, Thomas
name: Baartman, Richard A.
name: Koay, Hui Wen
name: Rao, Yi-Nong
name: Zhang, Lige
Publisher: name: arXiv
Year: 2022
Subjects: subject: Accelerator Physics (physics.acc-ph)
subject: FOS: Physical sciences

description: Compact H$^-$ cyclotrons are used all across the globe to produce medical isotopes. Machines with external ion sources have demonstrated average extracted currents on the order of a few mA, although reported operational numbers are typically around 1\,mA or below. To explore the possibility of extracting even more current from such cyclotrons, it is important to understand the mechanisms that drive intensity limits and how they scale. In this paper we review some of the key aspects of the beam dynamics in the central region of compact cyclotrons, including rf electric focusing and space charge effects. We derive the scaling of the phase acceptance with the rf gap voltage, harmonic number, etc. We also explore the scaling with different types of ions such as H$^-$, H$_2^+$ and H$_3^+$. We discuss the impact of mechanical erosion of the central region electrodes. Thoughout the paper, we use examples and experimental data from two compact H$^-$ cyclotrons for reference: the TR-30 series and the TRIUMF 500\,MeV machine.
HD 24355 observed by the Kepler K2 mission: A rapidly oscillating Ap star pulsating in a distorted quadrupole mode
Creators: name: Holdsworth, Daniel L.
name: Kurtz, Donald W.
name: Smalley, Barry
name: Saio, Hideyuki
name: Handler, Gerald
name: Murphy, Simon J.
name: Lehmann, Holger
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We present an analysis of the first Kepler K2 mission observations of a rapidly oscillating Ap (roAp) star, HD 24355 ($V=9.65$). The star was discovered in SuperWASP broadband photometry with a frequency of 224.31 d$^{-1}$, (2596.18 $μ$Hz; $P = 6.4$ min) and an amplitude of 1.51 mmag, with later spectroscopic analysis of low-resolution spectra showing HD 24355 to be an A5 Vp SrEu star. The high precision K2 data allow us to identify 13 rotationally split sidelobes to the main pulsation frequency of HD 24355. This number of sidelobes combined with an unusual rotational phase variation show this star to be the most distorted quadrupole roAp pulsator yet observed. In modelling this star, we are able to reproduce well the amplitude modulation of the pulsation, and find a close match to the unusual phase variations. We show this star to have a pulsation frequency higher than the critical cut-off frequency. This is currently the only roAp star observed with the Kepler spacecraft in Short Cadence mode that has a photometric amplitude detectable from the ground, thus allowing comparison between the mmag amplitude ground-based targets and the $μ$mag spaced-based discoveries. No further pulsation modes are identified in the K2 data, showing this star to be a single-mode pulsator.
description: 18 pages, accepted for publication in MNRAS
Temporal coupled-mode theory for thermal emission from multiple arbitrarily coupled resonators
Creators: name: Huang, Xin
name: Yeung, Christopher
name: Raman, Aaswath P.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Controlling the spectral response of thermal emitters has become increasingly important for a range of energy and sensing applications. Conventional approaches to achieving arbitrary spectrum selectivity in photonic systems have entailed combining multiple resonantly emissive elements together to achieve a range of spectral profiles through numerical optimization, with a universal theoretical framework lacking. Here, we develop a temporal coupled mode theory for thermal emission from multiple, arbtirarily-coupled resonators. We validate our theory against numerical simulations of complex two- and three-dimensional nanophotonic thermal emitters, highlighting the anomalous thermal emission spectra that can emerge when multiple resonators with arbitrary properties couple to each other with varying strengths.