cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
title: Topological Task Space Modelling for Autonomous Space Robot Action Planning
Creators: name: Matthiesen, Jan
Publisher: name: IFAC - International Federation of Automatic Control
Year: 2023

description: Future space robot generations will replace astronauts in deep space missions and routine operations. They will use tools, perform assembly, disassembly and handling tasks for maintenance and repair purposes, among others. A key feature of autonomous, task-level commandable maintenance robots is a valid and complete representation of an application's task space for planning and optimizing a rough action sequence facing a specific sensorially classified situation. This paper shows such a representation for a robot based automated material science experiment setup und proposes a method of analysis by which a valid and complete task space model can be obtained. Results of practical experiments with a terrestrial laboratory mock-up using the novel representation scheme are presented as well.
Computing the structured pseudospectrum of a Toeplitz matrix and its extreme points
Creators: name: Buttà, Paolo
name: Guglielmi, Nicola
name: Noschese, Silvia
Publisher: name: arXiv
Year: 2012
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics
subject: 65F15, 65L07

description: The computation of the structured pseudospectral abscissa and radius (with respect to the Frobenius norm) of a Toeplitz matrix is discussed and two algorithms based on a low rank property to construct extremal perturbations are presented. The algorithms are inspired by those considered in [SIAM J. Matrix Anal. Appl., 32 (2011), pp. 1166-1192] for the unstructured case, but their extension to structured pseudospectra and analysis presents several difficulties. Natural generalizations of the algorithms, allowing to draw significant sections of the structured pseudospectra in proximity of extremal points are also discussed. Since no algorithms are available in the literature to draw such structured pseudospectra, the approach we present seems promising to extend existing software tools (Eigtool, Seigtool) to structured pseudospectra representation for Toeplitz matrices. We discuss local convergence properties of the algorithms and show some applications to a few illustrative examples.
description: 21 pages, 11 figures
The Effect of Renal Denervation on Cardiac Remodeling and Function in Rats with Chronic Intermittent Hypoxia
Creators: name: Lu, Dasheng
Publisher: name: figshare
Year: 2022
Subjects: subject: 110201 Cardiology (incl. Cardiovascular Diseases)
subject: FOS: Clinical medicine

description: supplementary table. The primer sequence for RT-PCR
Generalized $k$-core pruning process on directed networks
Creators: name: Zhao, Jin-Hua
Publisher: name: arXiv
Year: 2017
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: The resilience of a complex interconnected system concerns the size of the macroscopic functioning node clusters after external perturbations based on a random or designed scheme. For a representation of the interconnected systems with directional or asymmetrical interactions among constituents, the directed network is a convenient choice. Yet how the interaction directions affect the network resilience still lacks thorough exploration. Here, we study the resilience of directed networks with a generalized $k$-core pruning process as a simple failure procedure based on both the in- and out-degrees of nodes, in which any node with an in-degree $< k_{in}$ or an out-degree $< k_{ou}$ is removed iteratively. With an explicitly analytical framework, we can predict the relative sizes of residual node clusters on uncorrelated directed random graphs. We show that the discontinuous transitions rise for cases with $k_{in} \geq 2$ or $k_{ou} \geq 2$, and the unidirectional interactions among nodes drive the networks more vulnerable against perturbations based on in- and out-degrees separately.
description: 21 pages, 8 figures, 1 table
Critical role of the exchange interaction for the electronic structure and charge-density-wave formation in TiSe2
Creators: name: Hellgren, Maria
name: Baima, Jacopo
name: Bianco, Raffaello
name: Calandra, Matteo
name: Mauri, Francesco
name: Wirtz, Ludger
Publisher: name: arXiv
Year: 2017
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We show that the inclusion of screened exchange via hybrid functionals provides a unified description of the electronic and vibrational properties of TiSe2. In contrast to local approximations in density functional theory, the explicit inclusion of exact, non-local exchange captures the effects of the electron-electron interaction needed to both separate the Ti-d states from the Se-p states and stabilize the charge-density-wave (CDW) (or low-T) phase through the formation of a p-d hybridized state. We further show that this leads to an enhanced electron-phonon coupling that can drive the transition even if a small gap opens in the high-T phase. Finally, we demonstrate that the hybrid functionals can generate a CDW phase where the electronic bands, the geometry, and the phonon frequencies are in agreement with experiments.
description: Supplemental Material included. To appear in Phys. Rev. Lett
Trajeto Kartonero [dissertação de mestrado]
Creators: name: Rodrigues, Evandro
Publisher: name: figshare
Year: 2023
Subjects: Literary studies not elsewhere classified

description: Este trabalho constitui uma pesquisa que procura, a partir do modo de ação de algumas editoras cartoneras, (re)conhecer o fenômeno denominado “cartonerismo”, movimento editorial, poético, filosófico, político e cultural que se desenvolve pela América Latina. Tratá-lo sob as perspectivas teóricas literárias contemporâneas, sobretudo da pós-modernidade, perfazendo uma leitura multilateral desses acontecimentos e pensamentos com referência às incidências críticas e estéticas em relação a algumas obras publicadas por estas editoras.
The Lyman Alpha Reference Sample. XVI. Global 21cm HI properties of Lyman-$α$ emitting galaxies
Creators: name: Reste, A. Le
name: Hayes, M. J.
name: Cannon, J. M.
name: Melinder, J.
name: Runnholm, A.
name: Rivera-Thorsen, T. E.
name: Östlin, G.
name: Adamo, A.
name: Herenz, E. C.
name: Schaerer, D.
name: Scarlata, C.
name: Kunth, D.
Publisher: name: arXiv
Year: 2024
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The Lyman-$α$ (Lya) line of hydrogen is a well-known tracer of galaxies at high-z. However, the connection between Lya observables and galaxy properties has not fully been established, limiting the use of the line to probe the physics of galaxies. Here, we derive global neutral hydrogen gas (HI) properties of nearby Lya-emitting galaxies to assess the impact of HI on the Lya output of galaxies. We observed 21cm line emission using the VLA in D-array configuration (~55" resolution, ~38 kpc) for 37 star-forming galaxies with available Lya imaging from the Lyman Alpha Reference Samples (LARS and eLARS). We detect 21cm emission for 33/37 galaxies observed. We find no significant correlation of global HI properties with Lya luminosity, escape fraction or equivalent width derived with HST photometry. Additionally, both Lya-emitters and weak or non-emitters are distributed evenly along the HI parameter space of optically-selected z=0 galaxies. Around 74% of the sample is undergoing galaxy interaction, this fraction is higher for Lya-emitters (83% for galaxies with EW$\geq$20Å) than for non or weak emitters (70%). Nevertheless, galaxies identified as interacting have Lya and HI properties statistically consistent with those of non-interacting galaxies. Our results show that global HI properties (on scales > 30kpc) have little direct impact on the Lya output from galaxies. Instead, HI likely regulates Lya emission on small scales: statistical comparisons of Lya and high angular resolution 21cm observations are required to fully assess the role of HI in Lya radiative transfer. While our study indicates that galaxy mergers could play a role in the emission of Lya photons in the local universe, especially for galaxies with high HI fractions, the line-of-sight through which a system is observed ultimately determines Lya observables.
description: 15+35 pages, 5+33 figures, Accepted for publication in A&A
Structured conditioning of Hamiltonian eigenvalue problems
Creators: name: Buttà, Paolo
name: Noschese, Silvia
Publisher: name: arXiv
Year: 2012
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics
subject: 65F15, 65F35

description: We discuss the effect of structure-preserving perturbations on complex or real Hamiltonian eigenproblems and characterize the structured worst-case effect perturbations. We derive significant expressions for both the structured condition numbers and the worst-case effect Hamiltonian perturbations. It is shown that, for purely imaginary eigenvalues, the usual unstructured perturbation analysis is sufficient.
description: 12 pages, 2 figures
Finding and Recommending Scholarly Articles
Creators: name: Kurtz, Michael J.
name: Henneken, Edwin A.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Information Retrieval (cs.IR)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Digital Libraries (cs.DL)
subject: Physics and Society (physics.soc-ph)
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences

description: The rate at which scholarly literature is being produced has been increasing at approximately 3.5 percent per year for decades. This means that during a typical 40 year career the amount of new literature produced each year increases by a factor of four. The methods scholars use to discover relevant literature must change. Just like everybody else involved in information discovery, scholars are confronted with information overload. Two decades ago, this discovery process essentially consisted of paging through abstract books, talking to colleagues and librarians, and browsing journals. A time-consuming process, which could even be longer if material had to be shipped from elsewhere. Now much of this discovery process is mediated by online scholarly information systems. All these systems are relatively new, and all are still changing. They all share a common goal: to provide their users with access to the literature relevant to their specific needs. To achieve this each system responds to actions by the user by displaying articles which the system judges relevant to the user's current needs. Recently search systems which use particularly sophisticated methodologies to recommend a few specific papers to the user have been called "recommender systems". These methods are in line with the current use of the term "recommender system" in computer science. We do not adopt this definition, rather we view systems like these as components in a larger whole, which is presented by the scholarly information systems themselves. In what follows we view the recommender system as an aspect of the entire information system; one which combines the massive memory capacities of the machine with the cognitive abilities of the human user to achieve a human-machine synergy.
description: 14 pages, part of the forthcoming MIT book "Bibliometrics and Beyond: Metrics-Based Evaluation of Scholarly Research" edited by Blaise Cronin and Cassidy R. Sugimoto
Trajeto Kartonero
Creators: name: Rodrigues, Evandro
Publisher: name: figshare
Year: 2023
Subjects: Literary studies not elsewhere classified

description: Este trabalho constitui uma pesquisa que procura, a partir do modo de ação de algumas editoras cartoneras, (re)conhecer o fenômeno denominado “cartonerismo”, movimento editorial, poético, filosófico, político e cultural que se desenvolve pela América Latina. Tratá-lo sob as perspectivas teóricas literárias contemporâneas, sobretudo da pós-modernidade, perfazendo uma leitura multilateral desses acontecimentos e pensamentos com referência às incidências críticas e estéticas em relação a algumas obras publicadas por estas editoras.
An analytically iterative method for solving problems of cosmic-ray modulation
Creators: name: Kolesnyk, Yuriy L.
name: Bobik, Pavol
name: Shakhov, Boris A.
name: Putis, Marian
Publisher: name: arXiv
Year: 2017
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: The development of an analytically iterative method for solving steady-state as well as unsteady-state problems of cosmic-ray (CR) modulation is proposed. Iterations for obtaining the solutions are constructed for the spherically symmetric form of the CR propagation equation. The main solution of the considered problem consists of the zero-order solution that is obtained during the initial iteration and amendments that may be obtained by subsequent iterations. The finding of the zero-order solution is based on the CR isotropy during propagation in the space, whereas the anisotropy is taken into account when finding the next amendments. To begin with, the method is applied to solve the problem of CR modulation where the diffusion coefficient $κ$ and the solar wind speed $u$ are constants with an Local Interstellar Spectra (LIS) spectrum. The solution obtained with two iterations was compared with an analytical solution and with numerical solutions. Finally, solutions that have only one iteration for two problems of CR modulation with $u = constant$ and the same form of LIS spectrum were obtained and tested against numerical solutions. For the first problem, $κ$ is proportional to the momentum of the particle $p$, so it has the form $κ=k_0η$, where $η=\frac{p}{m_0c}$. For the second problem, the diffusion coefficient is given in the form $κ=k_0βη$, where $β=\frac{v}{c}$ is the particle speed relative to the speed of light. There was a good matching of the obtained solutions with the numerical solutions as well as with the analytical solution for the problem where $κ= constant$.
description: 13 pages, 9 figures and 2 tables
Extending the Tutte and Bollobás-Riordan Polynomials to Rank 3 Weakly-Colored Stranded Graphs
Creators: name: Avohou, Remi C.
name: Geloun, Joseph Ben
name: Hounkonnou, Mahouton N.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Geometric Topology (math.GT)
subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 05C10, 57M15

description: The Bollobás-Riordan polynomial [Math. Ann. 323, 81 (2002)] is a universal polynomial invariant for ribbon graphs. We find an extension of this polynomial for a particular family of combinatorial objects, called rank 3 weakly-colored stranded graphs. Stranded graphs arise in the study of tensor models for quantum gravity in physics, and generalize graphs and ribbon graphs. We present a seven-variable polynomial invariant of these graphs, which obeys a contraction/deletion recursion relation similar to that of the Tutte and Bollobás-Riordan polynomials. However, it is defined on a much broader class of objects, and furthermore captures properties that are not encoded by the Tutte or Bollobás-Riordan polynomials.
description: 41 pages, 32 figures; improved version (published), some statements corrected
Screening, Hyperuniformity, and Instability in the Sedimentation of Irregular Objects
Creators: name: Goldfriend, Tomer
name: Diamant, Haim
name: Witten, Thomas A.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: We study the overdamped sedimentation of non-Brownian objects of irregular shape using fluctuating hydrodynamics. The anisotropic response of the objects to flow, caused by their tendency to align with gravity, directly suppresses concentration and velocity fluctuations. This allows the suspension to avoid the anomalous fluctuations predicted for suspensions of symmetric spheroids. The suppression of concentration fluctuations leads to a correlated, hyperuniform structure. For certain object shapes, the anisotropic response may act in the opposite direction, destabilizing uniform sedimentation.
description: 12 pages (6 main text + 6 supplemental material); 3 figures
Objectivity in non-Markovian spin-boson model
Creators: name: Lampo, Aniello
name: Tuziemski, Jan
name: Lewenstein, Maciej
name: Korbicz, Jaroslaw K.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Objectivity constitutes one of the main features of the macroscopic classical world. An important aspect of the quantum-to-classical transition issue is to explain how such a property arises from the microscopic quantum world. Recently, within the framework of open quantum systems, there has been proposed such a mechanism in terms of the, so-called, Spectrum Broadcast Structures. These are multipartite quantum states of the system of interest and a part of its environment, assumed to be under an observation. This approach requires a departure from the standard open quantum systems methods, as the environment cannot be completely neglected. In the present work we study the emergence of such a state-structures in one of the canonical models of the condensed matter theory: Spin-boson model, describing the dynamics of a two-level system coupled to an environment made up by a large number of harmonic oscillators. We pay much attention to the behavior of the model in the non-Markovian regime, in order to provide a testbed to analyze how the non-Markovian nature of the evolution affects the surfacing of a spectrum broadcast structure.
description: 11 pages, 13 figures
Supplementary material from Occam’s razor gets a new edge: the use of symmetries in model selection
Creators: name: Borgqvist, Johannes G.
name: Palmer, Sam
Publisher: name: The Royal Society
Year: 2022
Subjects: subject: Computational Biology
subject: 10202 Biological Mathematics
subject: FOS: Mathematics

description: We demonstrate the power of using symmetries for model selection in the context of mechanistic modelling. We analyse two different models called the power law model (PLM) and the immunological model (IM) describing the increase in cancer risk with age, due to mutation accumulation or immunosenescence, respectively. The IM fits several cancer types better than the PLM implying that it would be selected based on minimizing residuals. However, recently a symmetry-based method for model selection has been developed, which has been successfully used in an in silico setting to find the correct model when traditional model fitting has failed. Here, we apply this method in a real-world setting to investigate the mechanisms of carcinogenesis. First, we derive distinct symmetry transformations of the two models and then we select the model which not only fits the original data but is also invariant under transformations by its symmetry. Contrary to the initial conclusion, we conclude that the PLM realistically describes the mechanism underlying the colon cancer dataset. These conclusions agree with experimental knowledge, and this work demonstrates how a model selection criteria based on biological properties can be implemented using symmetries.
A Generalization of "Existence and Behavior of the Radial Limits of a Bounded Capillary Surface at a Corner"
Creators: name: Crenshaw, Julie N.
name: Echart, Alexandra K.
name: Lancaster, Kirk E.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics
subject: 35J93, 53A10, 49Q10

description: The principle existence theorem (i.e. Theorem 1) of "Existence and Behavior of the Radial Limits of a Bounded Capillary Surface at a Corner" (Pacific J. Math. Vol. 176, No. 1 (1996), 165-194) is extended to the case of a contact angle $γ$ which is not bounded away from $0$ and $π$ (and depends on position in a bounded domain $Ω\in {\bf R}^{2}$ with a convex corner at ${\cal O}=(0,0)$). The lower bound on the size of "side fans" (i.e. Theorem 2 in the above paper) is extended to case of such contact angles for convex and nonconvex corners.
description: 20 pages, 3 figures, removed Example 3, added more details in the proofs, slight modifications, submitted to the Pacific Journal of Mathematics
Degree sequences of random digraphs and bipartite graphs
Creators: name: McKay, Brendan D.
name: Skerman, Fiona
Publisher: name: arXiv
Year: 2013
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 05C80, 60C05, 60K30, 05C20, 05C07

description: We investigate the joint distribution of the vertex degrees in three models of random bipartite graphs. Namely, we can choose each edge with a specified probability, choose a specified number of edges, or specify the vertex degrees in one of the two colour classes. This problem can alternatively be described in terms of the row and sum columns of random binary matrix or the in-degrees and out-degrees of a random digraph, in which case we can optionally forbid loops. It can also be cast as a problem in random hypergraphs, or as a classical occupancy, allocation, or coupon collection problem. In each case, provided the two colour classes are not too different in size nor the number of edges too low, we define a probability space based on independent binomial variables and show that its probability masses asymptotically equal those of the degrees in the graph model almost everywhere. The accuracy is sufficient to asymptotically determine the expectation of any joint function of the degrees whose maximum is at most polynomially greater than its expectation.
description: Minor changes, mostly of exposition
A Minimal Model of Burst-Noise Induced Bistability
Creators: name: Falk, Johannes
name: Mendler, Marc
name: Drossel, Barbara
Publisher: name: arXiv
Year: 2016
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Biological Physics (physics.bio-ph)
subject: Molecular Networks (q-bio.MN)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: We investigate the influence of intrinsic noise on stable states of a one-dimensional dynamical system that shows in its deterministic version a saddle-node bifurcation between monostable and bistable behaviour. The system is a modified version of the Schlögl model, which is a chemical reaction system with only one type of molecule. The strength of the intrinsic noise is varied without changing the deterministic description by introducing bursts in the autocatalytic production step. We study the transitions between monostable and bistable behavior in this system by evaluating the number of maxima of the stationary probability distribution. We find that changing the size of bursts can destroy and even induce saddle-node bifurcations. This means that a bursty production of molecules can qualitatively change the dynamics of a chemical reaction system even when the deterministic description remains unchanged.
description: 7 pages, 9 figures
Front fluctuations for the stochastic Cahn-Hilliard equation
Creators: name: Bertini, L.
name: Brassesco, S.
name: Buttà, P.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Mathematical Physics (math-ph)
subject: Probability (math.PR)
subject: FOS: Physical sciences
subject: FOS: Mathematics
subject: 60H15, 35R60, 82C24

description: We consider the Cahn-Hilliard equation in one space dimension, perturbed by the derivative of a space and time white noise of intensity $ε^{\frac 12}$, and we investigate the effect of the noise, as $ε\to 0$, on the solutions when the initial condition is a front that separates the two stable phases. We prove that, given $γ< \frac 23$, with probability going to one as $ε\to 0$, the solution remains close to a front for times of the order of $ε^{-γ}$, and we study the fluctuations of the front in this time scaling. They are given by a one dimensional continuous process, self similar of order $\frac 14$ and non Markovian, related to a fractional Brownian motion and for which a couple of representations are given.
description: 33 pages
Radio Emission from Embryonic Super-Luminous Supernova Remnants
Creators: name: Omand, Conor M. B.
name: Kashiyama, Kazumi
name: Murase, Kohta
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: It has been widely argued that Type-I super-luminous supernovae (SLSNe-I) are driven by powerful central engines with a long-lasting energy injection after the core-collapse of massive progenitors. One of the popular hypotheses is that the hidden engines are fast-rotating pulsars with a magnetic field of $B\sim{10}^{13}-{10}^{15}$ G. Murase, Kashiyama & Meszaros (2016) showed that quasi-steady radio/submm emission from non-thermal electron-positron pairs in nascent pulsar wind nebulae can be used as a counterpart of such pulsar-driven supernovae (SNe). In this work, focusing on the nascent SLSN-I remnants, we examine constraints that can be placed by radio emission. We show that the Atacama Large Millimeter/submillimetre Array (ALMA) can detect the radio nebula from SNe at $D_{\rm L} \sim 1 \ \rm Gpc$ in a few years after the explosion, while the Jansky Very Large Array (VLA) can also detect the counterpart in a few decades. The proposed radio followup observation could solve the parameter degeneracy in the pulsar-driven SN model for optical/UV light curves, and could also give us clues to young neutron star scenarios for SLSNe-I and fast radio bursts.
description: 8 pages, 6 figures, accepted by MNRAS
Height fluctuations for the stationary KPZ equation
Creators: name: Borodin, Alexei
name: Corwin, Ivan
name: Ferrari, Patrik L.
name: Vető, Bálint
Publisher: name: arXiv
Year: 2014
Subjects: subject: Probability (math.PR)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: We compute the one-point probability distribution for the stationary KPZ equation (i.e. initial data H(0,X)=B(X), for B(X) a two-sided standard Brownian motion) and show that as time T goes to infinity, the fluctuations of the height function H(T,X) grow like T^{1/3} and converge to those previously encountered in the study of the stationary totally asymmetric simple exclusion process, polynuclear growth model and last passage percolation. The starting point for this work is our derivation of a Fredholm determinant formula for Macdonald processes which degenerates to a corresponding formula for Whittaker processes. We relate this to a polymer model which mixes the semi-discrete and log-gamma random polymers. A special case of this model has a limit to the KPZ equation with initial data given by a two-sided Brownian motion with drift beta to the left of the origin and b to the right of the origin. The Fredholm determinant has a limit for beta>b, and the case where beta=b (corresponding to the stationary initial data) follows from an analytic continuation argument.
description: 91 pages, 8 figures, corrected version according to the erratum 2021
Dynamical Evolution of the Debris Disk after a Satellite Catastrophic Disruption around Saturn
Creators: name: Hyodo, Ryuki
name: Charnoz, Sébastien
Publisher: name: arXiv
Year: 2017
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: The hypothesis of a recent origin of Saturn's rings and its mid-sized moons is actively debated. It was suggested that a proto-Rhea and a proto-Dione might have collided recently, giving birth to the modern system of mid-sized moons. It is also suggested that the rapid viscous spreading of the debris may have implanted mass inside Saturn's Roche limit, giving birth to the modern Saturn's ring system. However, this scenario has been only investigated in very simplified way for the moment. This paper investigates it in detail to assess its plausibility by using $N$-body simulations and analytical arguments. When the debris disk is dominated by its largest remnant, $N$-body simulations show that the system quickly re-accrete into a single satellite without significant spreading. On the other hand, if the disk is composed of small particles, analytical arguments suggest that the disk experiences dynamical evolutions in three steps. The disk starts significantly excited after the impact and collisional damping dominates over the viscous spreading. After the system flattens, the system can become gravitationally unstable when particles are smaller than $\sim$ 100 m. However, the particles grow faster than spreading. Then, the system becomes gravitationally stable again and accretion continues at a slower pace, but spreading is inhibited. Therefore, the debris is expected to re-accrete into several large bodies. In conclusion, our results show that such a scenario may not form the today's ring system. In contrast, our results suggest that today's mid-sized moons are likely re-accreted from such a catastrophic event.
description: 12 pages, 8 figures, accepted for publication in AJ
Differential equations for real-structured (and unstructured) defectivity measures
Creators: name: Buttà, Paolo
name: Guglielmi, Nicola
name: Manetta, Manuela
name: Noschese, Silvia
Publisher: name: arXiv
Year: 2014
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics
subject: 15A18, 65K05

description: Let $A$ be either a complex or real matrix with all distinct eigenvalues. We propose a new method for the computation of both the unstructured and the real-structured (if the matrix is real) distance $w_{\mathbb K}(A)$ (where ${\mathbb K}=\mathbb C$ if general complex matrices are considered and ${\mathbb K} ={\mathbb R}$ if only real matrices are allowed) of the matrix $A$ from the set of defective matrices, that is the set of those matrices with at least a multiple eigenvalue with algebraic multiplicity larger than its geometric multiplicity. For $0 < \varepsilon \le w_{\mathbb K}(A)$, this problem is closely related to the computation of the most ill-conditioned $\varepsilon$-pseudoeigenvalues of $A$, that is points in the $\varepsilon$-pseudospectrum of $A$ characterized by the highest condition number. The method we propose couples a system of differential equations on a low rank (possibly structured) manifold which computes the $\varepsilon$-pseudoeigenvalue of $A$ which is closest to coalesce, with a fast Newton-like iteration aiming to determine the minimal value $\varepsilon$ such that such an $\varepsilon$-pseudoeigenvalue becomes defective. The method has a local behaviour; this means that in general we find upper bounds for $w_{\mathbb K}(A)$. However, they usually provide good approximations, in those (simple) cases where we can check this. The methodology can be extended to a structured matrix where it is required that the distance is computed within some manifold defining the structure of the matrix. In this paper we extensively examine the case of real matrices but we also consider pattern structures. As far as we know there do not exist methods in the literature able to compute such distance.
description: 30 pages
Fermi-to-Bose crossover in a trapped quasi-2D gas of fermionic atoms
Creators: name: Turlapov, A. V.
name: Kagan, M. Yu.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Physics of many-body systems where particles are restricted to move in two spatial dimensions is challenging and even controversial: On one hand, neither long-range order nor Bose condensation may appear in infinite uniform 2D systems at finite temperature, on the other hand this does not prohibit superfluidity or superconductivity. Moreover, 2D superconductors, such as cuprates, are among the systems with highest critical temperatures. Ultracold atoms are a platform for studying 2D physics. Uniquely to other physical systems, quantum statistics may be completely changed in an ultracold gas: an atomic Fermi gas may be smoothly crossed over into a gas of Bose molecules (or dimers) by tuning interatomic interactions. We review recent experiments where such crossover has been demonstrated as well as critical phenomena in the Fermi-to-Bose crossover. We also present simple theoretical models describing the gas at different points of the crossover and compare the data to these and more advanced models.
description: Review for J. Phys.: Cond. Matt
Dynamical black holes in low-energy string theory
Creators: name: Aniceto, Pedro
name: Rocha, Jorge V.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We investigate time-dependent spherically symmetric solutions of the four-dimensional Einstein-Maxwell-axion-dilaton system, with the dilaton coupling that occurs in low-energy effective heterotic string theory. A class of dilaton-electrovacuum radiating solutions with a trivial axion, previously found by Güven and Yörük, is re-derived in a simpler manner and its causal structure is clarified. It is shown that such dynamical spacetimes featuring apparent horizons do not possess a regular light-like past null infinity or future null infinity, depending on whether they are radiating or accreting. These solutions are then extended in two ways. First we consider a Vaidya-like generalisation, which introduces a null dust source. Such spacetimes are used to test the status of cosmic censorship in the context of low-energy string theory. We prove that - within this family of solutions - regular black holes cannot evolve into naked singularities by accreting null dust, unless standard energy conditions are violated. Secondly, we employ S-duality to derive new time-dependent dyon solutions with a nontrivial axion turned on. Although they share the same causal structure as their Einstein-Maxwell-dilaton counterparts, these solutions possess both electric and magnetic charges.
description: 1+24 pages + appendices, 6 figures; v2: minor corrections, added reference, matches published version
Two-photon exchange corrections to elastic $e^-$-proton scattering: Full dispersive treatment of $πN$ states at low momentum transfers
Creators: name: Tomalak, O.
name: Pasquini, B.
name: Vanderhaeghen, M.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: We evaluate the pion-nucleon intermediate-state contribution to the two-photon exchange (TPE) correction in the elastic electron-nucleon scattering within a dispersive framework. We calculate the contribution from all $πN$ partial waves using the MAID parametrization. We provide the corresponding TPE correction to the unpolarized $e p$ scattering cross section in the region of low momentum transfer $ Q^2 \lesssim 0.064~\mathrm{GeV}^2$, where no analytical continuation into the unphysical region of the TPE scattering amplitudes is required. We compare our result in the forward angular region with an alternative TPE calculation, in terms of structure functions, and find a good agreement, indicating a small contribution at low $Q^2$ due to discontinuities beyond $ πN$. We also compare our results with empirical fits.
description: 34 pages, 14 figures, version published in Phys. Rev. D 95, 096001 (2017)
An optically-selected cluster catalog at redshift 0.1
Creators: name: Oguri, Masamune
name: Lin, Yen-Ting
name: Lin, Sheng-Chieh
name: Nishizawa, Atsushi J.
name: More, Anupreeta
name: More, Surhud
name: Hsieh, Bau-Ching
name: Medezinski, Elinor
name: Miyatake, Hironao
name: Jian, Hung-Yu
name: Lin, Lihwai
name: Takada, Masahiro
name: Okabe, Nobuhiro
name: Speagle, Joshua S.
name: Coupon, Jean
name: Leauthaud, Alexie
name: Lupton, Robert H.
name: Miyazaki, Satoshi
name: Price, Paul A.
name: Tanaka, Masayuki
name: Chiu, I-Non
name: Komiyama, Yutaka
name: Okura, Yuki
name: Tanaka, Manobu M.
name: Usuda, Tomonori
Publisher: name: arXiv
Year: 2017
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We present an optically-selected cluster catalog from the Hyper Suprime-Cam (HSC) Subaru Strategic Program. The HSC images are sufficiently deep to detect cluster member galaxies down to $M_*\sim 10^{10.2}M_\odot$ even at $z\sim 1$, allowing a reliable cluster detection at such high redshifts. We apply the CAMIRA algorithm to the HSC Wide S16A dataset covering $\sim 232$ deg$^2$ to construct a catalog of 1921 clusters at redshift $0.115$ that roughly corresponds to $M_{\rm 200m}\gtrsim 10^{14}h^{-1}M_\odot$. We confirm good cluster photometric redshift performance, with the bias and scatter in $Δz/(1+z)$ being better than 0.005 and 0.01 over most of the redshift range, respectively. We compare our cluster catalog with large X-ray cluster catalogs from XXL and XMM-LSS surveys and find good correlation between richness and X-ray properties. We also study the miscentering effect from the distribution of offsets between optical and X-ray cluster centers. We confirm the high ($>0.9$) completeness and purity for high mass clusters by analyzing mock galaxy catalogs.
description: 18 pages, 18 figures, accepted for publication in PASJ; cluster catalogs are available at http://www.slac.stanford.edu/~oguri/cluster/
Constraining secret gauge interactions of neutrinos by meson decays
Creators: name: Bakhti, Pouya
name: Farzan, Yasaman
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: Secret coupling of neutrinos to a new light vector boson, $Z'$, with a mass smaller than 100 MeV is motivated within a myriad of scenarios which are designed to explain various anomalies in particle physics and cosmology. Due to the longitudinal component of the massive vector boson, the rates of three-body decay of charged mesons ($M$) such as the pion and the kaon to the light lepton plus neutrino and $Z'$ ($M \to l νZ'$) are enhanced by a factor of $(m_M/m_{Z'})^2$. On the other hand, the standard two body decay $M \to l ν$ is suppressed by a factor of $(m_l/m_M)^2$ due to chirality. We show that in the case of ($M \to e νZ^\prime$), the enhancement of $m_M^4/m_e^2 m_{Z^\prime}^2\sim 10^8-10^{10}$ relative to two-body decay ($M \to e ν$) enables us to probe very small values of gauge coupling for $ν_e$. The strongest bound comes from the $R_K\equiv Br(K \to e +ν)/Br(K \to μ+ν)$ measurement in the NA62 experiment. The bound can be significantly improved by customized searches for signals of three-body charged meson decay into the positron plus missing energy in the NA62 and/or PIENU data.
description: 7 pages, 3 figures
Unimodular measures on the space of all Riemannian manifolds
Creators: name: Abert, Miklos
name: Biringer, Ian
Publisher: name: arXiv
Year: 2016
Subjects: subject: Geometric Topology (math.GT)
subject: Differential Geometry (math.DG)
subject: FOS: Mathematics
subject: 53C12, 28D99, 53C24

description: We study unimodular measures on the space $\mathcal M^d$ of all pointed Riemannian $d$-manifolds. Examples can be constructed from finite volume manifolds, from measured foliations with Riemannian leaves, and from invariant random subgroups of Lie groups. Unimodularity is preserved under weak* limits, and under certain geometric constraints (e.g. bounded geometry) unimodular measures can be used to compactify sets of finite volume manifolds. One can then understand the geometry of manifolds $M$ with large, finite volume by passing to unimodular limits. We develop a structure theory for unimodular measures on $\mathcal M^d$, characterizing them via invariance under a certain geodesic flow, and showing that they correspond to transverse measures on a foliated `desingularization' of $\mathcal M^d$. We also give a geometric proof of a compactness theorem for unimodular measures on the space of pointed manifolds with pinched negative curvature, and characterize unimodular measures supported on hyperbolic $3$-manifolds with finitely generated fundamental group.
description: 81 pages, updated with some minor changes and corrections
Modularity of regular and treelike graphs
Creators: name: McDiarmid, Colin
name: Skerman, Fiona
Publisher: name: arXiv
Year: 2016
Subjects: subject: Combinatorics (math.CO)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Social and Information Networks (cs.SI)
subject: Physics and Society (physics.soc-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: Clustering algorithms for large networks typically use modularity values to test which partitions of the vertex set better represent structure in the data. The modularity of a graph is the maximum modularity of a partition. We consider the modularity of two kinds of graphs. For $r$-regular graphs with a given number of vertices, we investigate the minimum possible modularity, the typical modularity, and the maximum possible modularity. In particular, we see that for random cubic graphs the modularity is usually in the interval $(0.666, 0.804)$, and for random $r$-regular graphs with large $r$ it usually is of order $1/\sqrt{r}$. These results help to establish baselines for statistical tests on regular graphs. The modularity of cycles and low degree trees is known to be close to 1: we extend these results to `treelike' graphs, where the product of treewidth and maximum degree is much less than the number of edges. This yields for example the (deterministic) lower bound $0.666$ mentioned above on the modularity of random cubic graphs.
description: 25 pages
MHD simulations of oscillating cusp-filling tori around neutron stars -- missing upper kHz QPO
Creators: name: Parthasarathy, Varadarajan
name: Kluzniak, Wlodek
name: Cemeljic, Miljenko
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We performed axisymmetric, grid-based, ideal magnetohydrodynamic (MHD) simulations of oscillating cusp-filling tori orbiting a non-rotating neutron star. A pseudo-Newtonian potential was used to construct the constant angular momentum tori in equilibrium. The inner edge of the torus is terminated by a "cusp" in the effective potential. The initial motion of the model tori was perturbed with uniform sub-sonic vertical and diagonal velocity fields. As the configuration evolved in time, we measured the mass accretion rate on the neutron star surface and obtained the power spectrum. The prominent mode of oscillation in the cusp torus is the radial epicyclic mode. It would appear that vertical oscillations are suppressed by the presence of the cusp. From our analysis it follows that the mass accretion rate carries a modulation imprint of the oscillating torus, and hence so does the boundary layer luminosity.
description: Accepted in MNRAS Letters. 5 pages, 3 figures, 1 table
Quantisation of derived Lagrangians
Creators: name: Pridham, J. P.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Algebraic Geometry (math.AG)
subject: Quantum Algebra (math.QA)
subject: FOS: Mathematics

description: We investigate quantisations of line bundles $\mathcal{L}$ on derived Lagrangians $X$ over $0$-shifted symplectic derived Artin $N$-stacks $Y$. In our derived setting, a deformation quantisation consists of a curved $A_{\infty}$ deformation of the structure sheaf $\mathcal{O}_{Y}$, equipped with a curved $A_{\infty}$ morphism to the ring of differential operators on $\mathcal{L}$; for line bundles on smooth Lagrangian subvarieties of smooth symplectic algebraic varieties, this simplifies to deforming $(\mathcal{L}, \mathcal{O}_{Y})$ to a DQ module over a DQ algebroid. For each choice of formality isomorphism between the $E_2$ and $P_2$ operads, we construct a map from the space of non-degenerate quantisations to power series with coefficients in relative cohomology groups of the respective de Rham complexes. When $\mathcal{L}$ is a square root of the dualising line bundle, this leads to an equivalence between even power series and certain anti-involutive quantisations, ensuring that the deformation quantisations always exist for such line bundles. This gives rise to a dg category of algebraic Lagrangians, an algebraic Fukaya category of the form envisaged by Behrend and Fantechi. We also sketch a generalisation of these quantisation results to Lagrangians on higher $n$-shifted symplectic derived stacks.
description: 61 pp; v2 minor additions and refs updated; v3 expanded generally, with some new material in final section; v4 further expanded, final version to appear in G&T
A precision determination of the Effect of Metallicity on Cepheid absolute magnitudes in VIJHK bands from Magellanic Cloud Cepheids
Creators: name: Wielgorski, Piotr
name: Pietrzynski, Grzegorz
name: Gieren, Wolfgang
name: Gorski, Marek
name: Kudritzki, Rolf-Peter
name: Zgirski, Bartlomiej
name: Bresolin, Fabio
name: Storm, Jesper
name: Matsunaga, Noriyuki
name: Graczyk, Dariusz
name: Soszynski, Igor
Publisher: name: arXiv
Year: 2017
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Using high-quality observed period-luminosity relations in both Magellanic Clouds in VIJHKs bands and optical and near-infrared Wesenheit indices we determine the effect of metallicity on Cepheid P-L relations by comparing the relative distance between LMC and SMC as determined from the Cepheids to the distance difference between the Clouds which has been derived with very high accuracy from late-type eclipsing binary systems. Within an uncertainty of 3% which is dominated by the uncertainty on the mean metallicity difference between the Cepheid populations in LMC and SMC we find metallicity effects smaller than 2% in all bands and in the Wesenheit indices, consistent with a zero metallicity effect. This result is valid for the metallicity range from -0.35 dex to -0.75 dex corresponding to the mean [Fe/H] values for classical Cepheids in LMC and SMC, respectively. Yet most Cepheids in galaxies beyond the Local Group and located in the less crowded outer regions of these galaxies do fall into this metallicity regime, making our result important for applications to determine the distances to spiral galaxies well beyond the Local Group. Our result supports previous findings which indicated a very small metallicity effect on the near-infrared absolute magnitudes of classical Cepheids, and resolves the dispute about the size and sign of the metallicity effect in the optical spectral range. It also resolves one of the most pressing problems in the quest towards a measurement of the Hubble constant with an accuracy of 1% from the Cepheid-supernova Ia method.
description: 13 pages, 3 figures, published in ApJ