cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Identification of an influence network using ensemble-based filtering for Hawkes processes driven by count data
Creators: name: N., Santitissadeekorn
name: S., Delahaies
name: B, Lloyd D. J.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Social and Information Networks (cs.SI)
subject: Applications (stat.AP)
subject: FOS: Computer and information sciences

description: Many networks have event-driven dynamics (such as communication, social media and criminal networks), where the mean rate of the events occurring at a node in the network changes according to the occurrence of other events in the network. In particular, events associated with a node of the network could increase the rate of events at other nodes, depending on their influence relationship. Thus, it is of interest to use temporal data to uncover the directional, time-dependent, influence structure of a given network while also quantifying uncertainty even when knowledge of a physical network is lacking. Typically, methods for inferring the influence structure in networks require knowledge of a physical network or are only able to infer small network structures. In this paper, we model event-driven dynamics on a network by a multidimensional Hawkes process. We then develop a novel ensemble-based filtering approach for a time-series of count data (i.e., data that provides the number of events per unit time for each node in the network) that not only tracks the influence network structure over time but also approximates the uncertainty via ensemble spread. The method overcomes several deficiencies in existing methods such as existing methods for inferring multidimensional Hawkes processes are too slow to be practical for any network over ~50 nodes, can only deal with timestamp data (i.e. data on just when events occur not the number of events at each node), and that we do not need a physical network to start with. Our method is massively parallelizable, allowing for its use to infer the influence structure of large networks (~10,000 nodes). We demonstrate our method for large networks using both synthetic and real-world email communication data.
description: to appear in Physica D: Nonlinear Phenomena. 22 pages, 15 figures
A generalised comparison principle for the Monge-Ampère equation and the pressure in 2D fluid flows
Creators: name: Ozanski, Wojciech
Publisher: name: arXiv
Year: 2016
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics

description: We extend the generalised comparison principle for the Monge-Ampère equation due to Rauch & Taylor (Rocky Mountain J. Math. 7, 1977) to nonconvex domains. From the generalised comparison principle we deduce bounds (from above and below) on solutions of the Monge-Ampère equation with sign-changing right-hand side. As a consequence, if the right-hand side is nonpositive (and does not vanish almost everywhere) then the equation equipped with constant boundary condition has no solutions. In particular, due to a connection between the two-dimensional Navier-Stokes equations and the Monge-Ampère equation, the pressure $p$ in 2D Navier-Stokes equations on a bounded domain cannot satisfy $Δp \leq 0$ in $Ω$ unless $Δp \equiv 0$ (at any fixed time). As a result at any time $t>0$ there exists $z\in Ω$ such that $Δp (z,t) =0$.
description: 15 pages, 2 figures
Dissipation in unsteady turbulence
Creators: name: Bos, Wouter
name: Rubinstein, Robert
Publisher: name: arXiv
Year: 2016
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: Recent experiments and simulations have shown that unsteady turbulent flows, before reaching a dynamic equilibrium state, display a universal behaviour. We show that the observed universal non-equilibrium scaling can be explained using a non-equilibrium correction of Kolmogorov's energy spectrum. Given the universality of the experimental and numerical observations, the ideas presented here lay the foundation for the modeling of a wide class of unsteady turbulent flows.
Absence of extended atmospheres in low-mass star radius-gap planets GJ 9827 b, GJ 9827 d and TOI-1235 b
Creators: name: Krishnamurthy, Vigneshwaran
name: Hirano, Teruyuki
name: Gaidos, Eric
name: Sato, Bunei
name: Kopparapu, Ravi
name: Barclay, Thomas
name: Garcia-Sage, Katherine
name: Harakawa, Hiroki
name: Hodapp, Klaus
name: Jacobson, Shane
name: Konishi, Mihoko
name: Kotani, Takayuki
name: Kudo, Tomoyuki
name: Kurokawa, Takashi
name: Kuzuhara, Masayuki
name: Lopez, Eric
name: Nishikawa, Jun
name: Omiya, Masashi
name: Schlieder, Joshua E.
name: Serizawa, Takuma
name: Tamura, Motohide
name: Ueda, Akitoshi
name: Vievard, Sebastien
Publisher: name: arXiv
Year: 2023
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: \textit{Kepler} showed a paucity of planets with radii of 1.5 - 2 $\mathrm R_{\oplus}$ around solar mass stars but this radius-gap has not been well studied for low-mass star planets. Energy-driven escape models like photoevaporation and core-powered mass-loss predict opposing transition regimes between rocky and non-rocky planets when compared to models depicting planets forming in gas-poor environments. Here we present transit observations of three super-Earth sized planets in the radius-gap around low-mass stars using high-dispersion InfraRed Doppler (IRD) spectrograph on the Subaru 8.2m telescope. The planets GJ 9827 b and d orbit around a K6V star and TOI-1235 b orbits a M0.5 star. We limit any planet-related absorption in the 1083.3 nm lines of triplet He I by placing an upper-limit on the equivalent width of 14.71 mÅ, 18.39 mÅ, and 1.44 mÅ, for GJ 9827 b (99% confidence), GJ 9827 d (99% confidence) and TOI-1235 b (95% confidence) respectively. Using a Parker wind model, we cap the mass-loss at $>$0.25 $\mathrm M_{\oplus}$ Gyr$^{-1}$ and $>$0.2 $\mathrm M_{\oplus}$ Gyr$^{-1}$ for GJ 9827 b and d, respectively (99% confidence), and $>$0.05 $\mathrm M_{\oplus}$ Gyr$^{-1}$ for TOI-1235 b (95\% confidence) for a representative wind temperature of 5000 K. Our observed results for the three planets are more consistent with the predictions from photoevaporation and/or core-powered mass-loss models than the gas-poor formation models. However, more planets in the radius-gap regime around the low-mass stars are needed to robustly predict the atmospheric evolution in planets around low-mass stars.
description: Published for MNRAS. 12 pages, 15 figures
The Lagrange multiplier and the stationary Stokes equations
Creators: name: Ozanski, Wojciech
Publisher: name: arXiv
Year: 2017
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics

description: We briefly discuss the notion of the Lagrange multiplier for a linear constraint in the Hilbert space setting, and we prove that the pressure $p$ appearing in the stationary Stokes equations is the Lagrange multiplier of the constraint $\mathrm{div}\, u =0$.
description: 4 pages
FIRM SURVIVAL AND ROLE OF CASH FLOW PLANNING IN OIL AND GAS FIRMS IN NIGERIA
Creators: name: Timothy, Chidubem Ugwu, Ph.D
name: Basilia, Chiamaka Nwachukwu, Ph.D.
Publisher: name: SADI Journal
Year: 2024
Subjects: Cash flow, Cash flow activities, Firms, Firm survival. Oil and gas. Cash flow, planning, Operating activities, Investing activities, Financing activities, Oil. Gas

description: The survival of any firm is predicated on how effectively management plans and controls its cash flow. While unhealthy cash flow will not only interrupt a company’s smooth operation, it can lead to total collapse. Thus, cash flows and their management assume prominence over the management of other current assets because cash is the most important asset that fertilizes a firm's survival. This work examined firm survival and the role of cash flow planning in the oil and gas sector in Nigeria. Net cash flow from operating activities (NCFOA), Net cash flow from investing activities (NCFIA), and Net cash flow from financing activities (NCFFA) were the independent variables, while profit for the year (PFTY) was the dependent variable and proxy for firm survival. Six (6) firms were selected from the eleven (11) oil and gas firms listed on the Nigerian Exchange Group (NGX) using a simple random sampling technique. The ex-Post facto research design was adopted. Data were extracted from the annual reports of the selected firms. Three hypotheses were formulated and analyzed using regression models. The results revealed that net NCFOA has a positive and significant effect on PFTY (r = 0.56585, p = 0.000001 < 0.05). NCFIA has a negative and non-significant effect on PFTY (r = -0.221256, p = 0.7032 > 0.05), while NCFFA has a negative and significant effect on PFTY (r = -0.536447, p = 0.0000 < 0.05). The implications of the findings include that an increase in NCFOA will enhance firm survival, while survival is negatively and significantly affected by financing activities. The study recommends that Managers of oil and gas firms in Nigeria should explore more value chains, get new channels for marketing, and reduce production costs in other to generate more NCFOA. Financing cash flow activities should be properly planned and a cheaper source of funding should be sorted to reduce the cost of servicing debt.
Lecture notes on topological recursion and geometry
Creators: name: Borot, Gaëtan
Publisher: name: arXiv
Year: 2017
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences
subject: 05Axx, 14N35, 32G15, 51Pxx, 53Dxx, 81T40

description: These are lecture notes for a 4h mini-course held in Toulouse, May 9-12th, at the thematic school on "Quantum topology and geometry". The goal of these lectures is to (a) explain some incarnations, in the last ten years, of the idea of topological recursion: in two dimensional quantum field theories, in cohomological field theories, in the computation of Weil-Petersson volumes of the moduli space of curves; (b) relate them more specifically to Eynard-Orantin topological recursion (revisited from Kontsevich-Soibelman point of view based on quantum Airy structures).
description: 48 pages, 16 figures
On weak solutions to the Navier-Stokes inequality with internal singularities
Creators: name: Ożański, Wojciech S.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics

description: We construct weak solutions to the Navier-Stokes inequality, $$ u\cdot \left(\partial_t u -νΔu + (u\cdot \nabla) u +\nabla p \right) \leq 0 $$ in $\mathbb{R}^3$, which blow up at a single point $(x_0,T_0)$ or on a set $S \times \{T_0 \}$, where $S\subset \mathbb{R}^3$ is a Cantor set whose Hausdorff dimension is at least $ξ$ for any preassigned $ξ\in (0,1)$. Such solutions were constructed by Scheffer, Comm. Math. Phys., 1985 & 1987. Here we offer a simpler perspective on these constructions. We sharpen the approach to construct smooth solutions to the Navier-Stokes inequality on the time interval $[0,1]$ satisfying the "approximate equality" $$ \left\| u\cdot \left(\partial_t u-νΔu + (u\cdot \nabla) u +\nabla p \right) \right\|_{L^\infty}\leq \vartheta, $$ and the "norm inflation" $\| u(1) \|_{L^\infty} \geq \mathcal{N} \| u(0) \|_{L^\infty}$ for any preassigned $\mathcal{N}>0$, $\vartheta >0$. Furthermore we extend the approach to construct a weak solution to the Euler inequality $$u\cdot \left(\partial_t u+ (u\cdot \nabla) u +\nabla p \right) \leq 0, $$ which satisfies the approximate equality with $ν=0$ and blows up on the Cantor set $S\times \{T_0 \}$ as above.
description: 86 pages, 23 figures
Royal Botanic Gardens, Melbourne : A critical review of their objectives and management past, present and the future
Creators: name: Hodges, Ronald Graham.
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.
Non-Refoulement as a Qualifier of Nation-State Sovereignty: The Case of Mass Population Flows
Creators: name: Ben-Nun, Gilad
Publisher: name: Leipziger Universitätsverlag
Year: 2017

description: Dieser Überblick zum historischen Forschungsstand beschreibt die Dynamiken der Flüchtlingspolitik während der Krise, die die Verfolgungen und Vertreibungen in Nazi-Deutschland auslöste. Die Historiographie zu diesem Gegenstand ist noch immer stark von nationalen Perspektiven geprägt, wobei jedes Land seine eigenen Narrative und Analysen produziert. Eine vergleichende Studie durch Experten nationaler Fälle hat die Ähnlichkeiten und Unterschiede in den Politiken verschiedener Staaten herausgearbeitet und gleichzeitig gezeigt, dass diese sich in starkem Maße an den Entscheidungen ihrer Nachbarn ausgerichtet haben. Der Artikel liefert eine Synthese dieser Untersuchung, integriert neue Forschungsresultate und bewertet die Verdienste des internationalen Flüchtlingsregimes dieser Zeit neu, das bislang nur ungenügende Aufmerksamkeit in der historischen Forschung gefunden hat.
description: Comparativ, Vol 27 No 1 (2017): Modern Refugees as Challengers of Nation-State Sovereignty: From the Historical to the Contemporary
Detection of HI in Emission in the Lyman Alpha Emitting Galaxy Haro 11
Creators: name: Pardy, Stephen A.
name: Cannon, John M.
name: Östlin, Göran
name: Hayes, Matthew
name: Bergvall, Nils
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present the first robust detection of HI 21 cm emission in the blue compact galaxy Haro 11 using the 100m Robert C. Byrd Green Bank Telescope (GBT). Haro 11 is a luminous blue compact galaxy with emission in both Lyman Alpha and the Lyman continuum. We detect (5.1 $\pm$ 0.7 $\times$10$^8$) M$_{\odot}$ of HI gas at an assumed distance of 88 Mpc, making this galaxy HI deficient compared to other local galaxies with similar optical properties. Given this small HI mass, Haro 11 has an elevated M$_{H2}$/M$_{HI}$ ratio and a very low gas fraction compared to most local galaxies, and contains twice as much mass in ionized hydrogen as in neutral hydrogen. The HI emission has a linewidth of 71 kms$^{-1}$ and is offset 60 kms$^{-1}$ redward of the optical line center. It is undergoing a starburst after a recent merger which has elevated the star formation rate, and will deplete the gas supply in $
description: 9 pages, 7 figures, accepted in AJ
Searching for the nature of stars with debris disks and planets
Creators: name: de la Reza, R.
name: Chavero, C.
name: Roca-Fàbrega, S.
name: de Andrés, F. Llorente
name: Cruz, P.
name: Cifuentes, C.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The nature of the few known solar-mass stars simultaneously containing debris disks and planets remains an open question. A number of works have shown that this property appears to be independent of planetary masses as well as of stellar age, but possible correlations with stellar kinematics and metallicity have not been investigated. In this paper, we show that the majority of known stars containing both debris disks and planets belong to the metal-enriched Galactic thin disk. The few exceptions are stars that seem to be born in the star formation peak occurring in times of thick disk formation (i.e., HD 10700, HD 20794, and HD 40307), that is, between 11 and 8 Gyr. The mass of the dusty disk of these three old stars measured at 70 $μ$m is very small - in fact, it is lower than that of the Kuiper belt of our Solar system by several orders of magnitude. These results are not surprising, as they remain within the values expected for the stellar disk evolution of such primitive stars. In parallel, we found another six thick-disk stars containing only debris disks or planets. These results enable us to establish a correlation between stellar metallicity and the mass of the dust disk modulated by the different formation epochs of the thick and thin Galactic disks.
description: 13 pages, 5 figures
Leray's fundamental work on the Navier-Stokes equations: a modern review of "Sur le mouvement d'un liquide visqueux emplissant l'espace"
Creators: name: Ożański, Wojciech S.
name: Pooley, Benjamin C.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics

description: This article offers a modern perspective which exposes the many contributions of Leray in his celebrated work on the Navier--Stokes equations from 1934. Although the importance of his work is widely acknowledged, the precise contents of his paper are perhaps less well known. The purpose of this article is to fill this gap. We follow Leray's results in detail: we prove local existence of strong solutions starting from divergence-free initial data that is either smooth, or belongs to $H^1$, $L^2\cap L^p$ (with $p\in(3,\infty]$), as well as lower bounds on the norms $\| \nabla u (t) \|_2$, $\| u(t) \|_p$ ($p\in(3,\infty]$) as $t$ approaches a putative blow-up time. We show global existence of a weak solution and weak-strong uniqueness. We present Leray's characterisation of the set of singular times for the weak solution, from which we deduce that its upper box-counting dimension is at most $\tfrac{1}{2}$. Throughout the text we provide additional details and clarifications for the modern reader and we expand on all ideas left implicit in the original work, some of which we have not found in the literature. We use some modern mathematical tools to bypass some technical details in Leray's work, and thus expose the elegance of his approach.
description: 81 pages. All comments are welcome
How tetraquarks can generate a second chiral phase transition
Creators: name: Pisarski, Robert D.
name: Skokov, Vladimir V.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We consider how tetraquarks can affect the chiral phase transition in theories like QCD, with light quarks coupled to three colors. For two flavors the tetraquark field is an isosinglet, and its effect is minimal. For three flavors, however, the tetraquark field transforms in the same representation of the chiral symmetry group as the usual chiral order parameter, and so for very light quarks there may be two chiral phase transitions, which are both of first order. In QCD, results from the lattice indicate that any transition from the tetraquark condensate is a smooth crossover. In the plane of temperature and quark chemical potential, though, a crossover line for the tetraquark condensate is naturally related to the transition line for color superconductivity. For four flavors we suggest that a triquark field, antisymmetric in both flavor and color, combine to form hexaquarks.
description: 34 pages, 4 figures
How the Refugees Crisis from Nazi Germany got (partly) solved through International Concertation
Creators: name: Caestecker, Frank
Publisher: name: Leipziger Universitätsverlag
Year: 2017

description: Dieser Überblick zum historischen Forschungsstand beschreibt die Dynamiken der Flüchtlingspolitik während der Krise, die die Verfolgungen und Vertreibungen in Nazi-Deutschland auslöste. Die Historiographie zu diesem Gegenstand ist noch immer stark von nationalen Perspektiven geprägt, wobei jedes Land seine eigenen Narrative und Analysen produziert. Eine vergleichende Studie durch Experten nationaler Fälle hat die Ähnlichkeiten und Unterschiede in den Politiken verschiedener Staaten herausgearbeitet und gleichzeitig gezeigt, dass diese sich in starkem Maße an den Entscheidungen ihrer Nachbarn ausgerichtet haben. Der Artikel liefert eine Synthese dieser Untersuchung, integriert neue Forschungsresultate und bewertet die Verdienste des internationalen Flüchtlingsregimes dieser Zeit neu, das bislang nur ungenügende Aufmerksamkeit in der historischen Forschung gefunden hat.
description: Comparativ, Vol 27 No 1 (2017): Modern Refugees as Challengers of Nation-State Sovereignty: From the Historical to the Contemporary
Partial regularity for a surface growth model
Creators: name: Ożański, W. S.
name: Robinson, J. C.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics

description: We prove two partial regularity results for the scalar equation $u_t+u_{xxxx}+\partial_{xx}u_x^2=0$, a model of surface growth arising from the physical process of molecular epitaxy. We show that the set of space-time singularities has (upper) box-counting dimension no larger than $7/6$ and $1$-dimensional (parabolic) Hausdorff measure zero. These parallel the results available for the three-dimensional Navier--Stokes equations. In fact the mathematical theory of the surface growth model is known to share a number of striking similarities with the Navier--Stokes equations, and the partial regularity results are the next step towards understanding this remarkable similarity. As far as we know the surface growth model is the only lower-dimensional "mini-model" of the Navier--Stokes equations for which such an analogue of the partial regularity theory has been proved. In the course of our proof, which is inspired by the rescaling analysis of Lin (1998) and Ladyzhenskaya & Seregin (1999), we develop certain nonlinear parabolic Poincaré inequality, which is a concept of independent interest. We believe that similar inequalities could be applicable in other parabolic equations.
description: 29 pages
Exploring the State of the Art in Legal QA Systems
Creators: name: Abdallah, Abdelrahman
name: Piryani, Bhawna
name: Jatowt, Adam
Publisher: name: arXiv
Year: 2023
Subjects: subject: Computation and Language (cs.CL)
subject: FOS: Computer and information sciences

description: Answering questions related to the legal domain is a complex task, primarily due to the intricate nature and diverse range of legal document systems. Providing an accurate answer to a legal query typically necessitates specialized knowledge in the relevant domain, which makes this task all the more challenging, even for human experts. Question answering (QA) systems are designed to generate answers to questions asked in human languages. QA uses natural language processing to understand questions and search through information to find relevant answers. QA has various practical applications, including customer service, education, research, and cross-lingual communication. However, QA faces challenges such as improving natural language understanding and handling complex and ambiguous questions. Answering questions related to the legal domain is a complex task, primarily due to the intricate nature and diverse range of legal document systems. Providing an accurate answer to a legal query typically necessitates specialized knowledge in the relevant domain, which makes this task all the more challenging, even for human experts. At this time, there is a lack of surveys that discuss legal question answering. To address this problem, we provide a comprehensive survey that reviews 14 benchmark datasets for question-answering in the legal field as well as presents a comprehensive review of the state-of-the-art Legal Question Answering deep learning models. We cover the different architectures and techniques used in these studies and the performance and limitations of these models. Moreover, we have established a public GitHub repository where we regularly upload the most recent articles, open data, and source code. The repository is available at: \url{https://github.com/abdoelsayed2016/Legal-Question-Answering-Review}.
title: Digitalization: Implications for Monetary Policy
Creators: name: Chu, Vivian
name: Dahlhaus, Tatjana
name: Hajzler, Christopher
name: Yanni, Pierre-Yves
Publisher: name: Bank of Canada
Year: 2023

description: We explore the implications of digitalization for monetary policy, both in terms of how monetary policy affects the economy and in terms of data analysis and communication with the public.
description: Nous explorons les implications de la numérisation pour la politique monétaire, à la fois en ce qui a trait à l’effet de la politique monétaire sur l’économie et en termes d’analyse des données et de communication avec le public.
Shapes of unit lattices and escape of mass
Creators: name: David, Ofir
name: Shapira, Uri
Publisher: name: arXiv
Year: 2016
Subjects: subject: Number Theory (math.NT)
subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics

description: We study the collection of points on the modular surface obtained from the logarithm embeddings of the groups of units in totally real cubic number fields. We conjecture that this set is dense and show that its closure contains countably many explicit curves and give a strategy to show that it has non-empty interior. The results are obtained by constructing explicit families of orders (generalizing the so called simplest cubic fields) and calculating their groups of units. We also address the question of escape of mass for the compact orbits of the diagonal group associated to these orders.
description: 29 pages, 2 figures
The Legal Status of Russian Refugees, 1921–1936
Creators: name: White, Elizabeth
Publisher: name: Leipziger Universitätsverlag
Year: 2017

description: Dieser Aufsatz untersucht die rechtlichen Lösungen, die die High Commission for Refugees in der Zwischenkriegszeit für den Verbleib von Hundertausenden von Flüchtlingen, die aus dem früheren Russischen und dem Osmanischen Reich nach Europa gekommen waren. Diese Flüchtlinge galten als Staatenlose in einer Welt, in der Rechte davon abhingen, dass ein Staat Individuen schützt. Russische Flüchtlingsanwälte und Rechtsexperten beteiligten sich in dieser Phase an einer juristischen Definition der Kategorie Flüchtling und versuchten ihm Rechte wie das der freien Bewegung, des Verbotes der Reziprozität von Vertreibung und das Recht auf Arbeit zu sichern. Sie überzeugten europäische Staaten Grenzen ihrer staatlichen Souveränität zu akzeptieren, so dass Staaten in den 920er und 930er Jahren ihr Einverständnis zu Arrangements und Konventionen gaben, die einen speziellen Schutz für Flüchtlinge in ihrer Gesetzgebung vorsahen. Damit wurden die Grundlagen für den Rechtsschutz der Flüchtlinge im 20. Jahrhundert geschaffen.
description: Comparativ, Vol 27 No 1 (2017): Modern Refugees as Challengers of Nation-State Sovereignty: From the Historical to the Contemporary
Derived counterparts of fusion categories of quantum groups
Creators: name: Arias, Juan Camilo
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Algebra (math.QA)
subject: FOS: Mathematics

description: In this text, we study derived versions of the fusion category associated to Lusztig's quantum group $\textbf{U}_q$. The categories that so arise are non-semisimple but recovers the usual fusion ring when passing to complexified Grothendieck rings. On the derived level it turns out that it is possible to define fusion for $\textbf{U}_q$ without using the notion of tilting modules. Hence, we arrive at a definition of the fusion ring that makes sense in any spherical category. We apply this new definition to the small quantum group and we related with some rings of A. Lachowska.
Clockwork Inflation
Creators: name: Kehagias, Alex
name: Riotto, Antonio
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We investigate the recently proposed clockwork mechanism delivering light degrees of freedom with suppressed interactions and show, with various examples, that it can be efficiently implemented in inflationary scenarios to generate flat inflaton potentials and small density perturbations without fine-tunings. We also study the clockwork graviton in de Sitter and, interestingly, we find that the corresponding clockwork charge is site-dependent. As a consequence, the amount of tensor modes is generically suppressed with respect to the standard cases where the clockwork set-up is not adopted. This point can be made a virtue in resurrecting models of inflation which were supposed to be ruled out because of the excessive amount of tensor modes from inflation.
description: 19 pages, 1 fugure
Sweeping Horndeski Canvas: New Growth-Rate Parameterization for Modified-Gravity Theories
Creators: name: Wen, Yuewei
name: Nguyen, Nhat-Minh
name: Huterer, Dragan
Publisher: name: arXiv
Year: 2023
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We propose and numerically validate a new fitting formula that is sufficiently accurate to model the growth of structure in Horndeski theories of modified gravity for upcoming Stage IV and V large-scale structure surveys. Based on an analysis of more than 18,000 Horndeski models and adopting the popular parameterization of the growth rate $f(z) = Ω_{M}(z)^γ$, we generalize the constant growth index $γ$ to a two-parameter redshift-dependent quantity, $γ(z)$, that more accurately fits these models. We demonstrate that the functional form $γ(z)=γ_0+γ_1z^2 / (1+z)$ improves the median $χ^2$ of the fit to viable Horndeski models by a factor of $\sim40$ relative to that of a constant $γ$, and is sufficient to obtain unbiased results even for precise measurements expected in Stage IV and V surveys. Finally, we constrain the parameters of the new fitting formula using current cosmological data.
description: 23 pages, 6 figures; prepared for JCAP submission; comments welcome! v2: Add missing footnote on author role on the first page; fix latex package rendering error in a section title. v3: Match the version accepted to JCAP; correct repeated references
Unified role of Green's function poles and zeros in topological insulators
Creators: name: Blason, Andrea
name: Fabrizio, Michele
Publisher: name: arXiv
Year: 2023
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Green's function zeros, which can emerge only if correlation is strong, have been for long overlooked and believed to be devoid of any physical meaning, unlike Green's function poles. Here, we prove that Green's function zeros instead contribute on the same footing as poles to determine the topological character of an insulator. The key to the proof, worked out explicitly in 2D but easily extendable in 3D, is to express the topological invariant in terms of a quasiparticle thermal Green's function matrix $G_*(iε,\mathbf{k})= 1/\big(iε-H_*(ε,\mathbf{k})\big)$, with hermitian $H_*(ε,\mathbf{k})$, by filtering out the positive definite quasiparticle residue. In that way, the topological invariant is easily found to reduce to the TKNN formula for quasiparticles described by the non-interacting Hamiltonian $H_*(0,\mathbf{k})$. Since the poles of the quasiparticle Green's function $G_*(ε,\mathbf{k})$ on the real frequency axis correspond to poles and zeros of the physical-particle Green's function $G(ε,\mathbf{k})$, both of them equally determine the topological character of an insulator.
description: 12 pages, 2 figures
Cosmology with Peculiar Velocities: Observational Effects
Creators: name: Andersen, Per
name: Davis, Tamara M.
name: Howlett, Cullan
Publisher: name: arXiv
Year: 2016
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: In this paper we investigate how observational effects could possibly bias cosmological inferences from peculiar velocity measurements. Specifically, we look at how bulk flow measurements are compared with theoretical predictions. Usually bulk flow calculations try to approximate the flow that would occur in a sphere around the observer. Using the Horizon Run 2 simulation we show that the traditional methods for bulk flow estimation can overestimate the magnitude of the bulk flow for two reasons: when the survey geometry is not spherical (the data do not cover the whole sky), and when the observations undersample the velocity distributions. Our results may explain why several bulk flow measurements found bulk flow velocities that seem larger than those expected in standard ΛCDM cosmologies. We recommend a different approach when comparing bulk flows to cosmological models, in which the theoretical prediction for each bulk flow measurement is calculated specifically for the geometry and sampling rate of that survey. This means that bulk flow values will not be comparable between surveys, but instead they are comparable with cosmological models, which is the more important measure.
description: 11 pages, 5 figures. Accepted for publication in MNRAS
Simple maps, Hurwitz numbers, and Topological Recursion
Creators: name: Borot, Gaëtan
name: Garcia-Failde, Elba
Publisher: name: arXiv
Year: 2017
Subjects: subject: Mathematical Physics (math-ph)
subject: Algebraic Geometry (math.AG)
subject: Combinatorics (math.CO)
subject: FOS: Physical sciences
subject: FOS: Mathematics
subject: 05Axx, 14C17, 14N10, 14Q05, 15B52, 46L54

description: We introduce the notion of fully simple maps, which are maps with non self-intersecting disjoint boundaries. In contrast, maps where such a restriction is not imposed are called ordinary. We study in detail the combinatorics of fully simple maps with topology of a disk or a cylinder. We show that the generating series of simple disks is given by the functional inversion of the generating series of ordinary disks. We also obtain an elegant formula for cylinders. These relations reproduce the relation between moments and free cumulants established by Collins et al. math.OA/0606431, and implement the symplectic transformation $x \leftrightarrow y$ on the spectral curve in the context of topological recursion. We conjecture that the generating series of fully simple maps are computed by the topological recursion after exchange of $x$ and $y$. We propose an argument to prove this statement conditionally to a mild version of symplectic invariance for the $1$-hermitian matrix model, which is believed to be true but has not been proved yet. Our argument relies on an (unconditional) matrix model interpretation of fully simple maps, via the formal hermitian matrix model with external field. We also deduce a universal relation between generating series of fully simple maps and of ordinary maps, which involves double monotone Hurwitz numbers. In particular, (ordinary) maps without internal faces -- which are generated by the Gaussian Unitary Ensemble -- and with boundary perimeters $(λ_1,\ldots,λ_n)$ are strictly monotone double Hurwitz numbers with ramifications $λ$ above $\infty$ and $(2,\ldots,2)$ above $0$. Combining with a recent result of Dubrovin et al. math-ph/1612.02333, this implies an ELSV-like formula for these Hurwitz numbers.
description: 66 pages, 7 figures
Effects of clustered nuclear geometry on the anisotropic flow in O-O collisions at the LHC within a multiphase transport model framework
Creators: name: Behera, Debadatta
name: Prasad, Suraj
name: Mallick, Neelkamal
name: Sahoo, Raghunath
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: High Energy Physics - Theory (hep-th)
subject: Nuclear Experiment (nucl-ex)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: To understand the true origin of flowlike signatures and applicability of hydrodynamics in small collision systems, effects of soft QCD dynamics, the sensitivity of jetlike correlations, and nonequilibrium effects, efforts are being made to perform \textit{p}-O and O-O collisions at the LHC and RHIC energies. It is equally interesting to look into the possible signatures of an $α$-clustered nuclear geometry in $^{16}$O-$^{16}$O collisions by studying the initial-state effects on the final-state observables. In this work, within a multiphase transport model, we implement an $α$-cluster tetrahedral density profile in the oxygen nucleus along with the default Woods-Saxon density profile. We study the eccentricity ($ε_2$), triangularity ($ε_3$), normalized symmetric cumulants [NSC(2,3)], elliptic flow ($v_2$), and triangular flow ($v_3$) in $^{16}$O-$^{16}$O collisions at $\sqrt{s_{\rm NN}} = 7~$TeV. The constituent quark number scaling of the elliptic flow is also reported. For the most central collisions, enhanced effects in $\langle ε_3 \rangle/ \langle ε_2 \rangle$ and $\langle v_3 \rangle/ \langle v_2 \rangle$ with a negative value of NSC(2,3), and an away-side broadening in the two-particle azimuthal correlation function [$C(Δϕ)$] of the identified particles are observed in the presence of an $α$-clustered geometry.
description: Same as the published version in Phys. Rev. D
Teachers’ Feedback and Trainees’ Confidence: Do They Match?
Creators: name: Haro-Soler, María del Mar
Publisher: name: figshare
Year: 2024
Subjects: classificationCode: 470321
subject: Translation and interpretation studies

description: A quasi-experimental field study was performed before the outbreak of the pandemic in three groups of the same course: one offered traditional classes, whereas the other two included blended learning, in order to analyse how feedback could influence the students' confidence in each mode. Following the essence of action-research, the results of this first phase were implemented in an online translation course during the pandemic. After comparing and contrasting the results obtained in these two phases, we can conclude that indirect, elaborate and dialogic feedback fostered the students’ self-efficacy beliefs, irrespective of the educational mode.
From Land Reform to Veterinarians Without Borders in Cold War Afghanistan
Creators: name: Nunan, Timothy
Publisher: name: Leipziger Universitätsverlag
Year: 2017

description: Der Beitrag untersucht die Geschichte ländlicher Entwicklungspolitik anhand der Landreformen in Afghanistan während des Kalten Krieges. Während des zwanzigsten Jahrhunderts lebte die überwiegende Mehrheit der afghanischen Bevölkerung von der Landwirtschaft. Grundbesitz war jedoch höchst ungleich verteilt. Der Kalte Krieg verwandelte Afghanistan in ein Schlachtfeld westlicher und sowjetischer Visionen ländlicher Entwicklungsprojekte etwa im Bereich der Bewässerung oder der Einrichtung von Staatsgütern. Afghanische sozialistische Intellektuelle forderten eine umfassende Landreform, um die Probleme der ländlichen Bevölkerung zu lindern. Nach einem sozialistischen coup d’état im Jahre 978 versuchten sie, ihren radikalen Plan einer Umverteilung von Land auch gegen die moderateren Vorschläge der sowjetischen Berater durchzusetzen. Die Geschichte ländlicher Entwicklungspolitik im Afghanistan des Kalten Krieges führt sozialistische Entwürfe in die globale Geschichte der Entwicklungspolitik ein. Sie zeigt, dass für viele Akteure die Umverteilung von Land ein zentraler Aspekt der Entwicklungspolitik war. Und sie verweist darauf, dass sich die Sowjetunion ungeachtet ihrer Erfahrungen mit kollektiver Landwirtschaft sehr reaktiv zu den Forderungen radikaler Akteure des globalen Südens verhielt, um Lösungen für ländliche Armut und soziale Gerechtigkeit zu inden.
description: Comparativ, Vol 27 No 2 (2017): Rural Development in the Twentieth Century: International Perspectives
Simulating Stellar Merger using HPX/Kokkos on A64FX on Supercomputer Fugaku
Creators: name: Diehl, Patrick
name: Daiß, Gregor
name: Huck, Kevin
name: Marcello, Dominic
name: Shiber, Sagiv
name: Kaiser, Hartmut
name: Pflüger, Dirk
Publisher: name: arXiv
Year: 2023
Subjects: subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences

description: The increasing availability of machines relying on non-GPU architectures, such as ARM A64FX in high-performance computing, provides a set of interesting challenges to application developers. In addition to requiring code portability across different parallelization schemes, programs targeting these architectures have to be highly adaptable in terms of compute kernel sizes to accommodate different execution characteristics for various heterogeneous workloads. In this paper, we demonstrate an approach to code and performance portability that is based entirely on established standards in the industry. In addition to applying Kokkos as an abstraction over the execution of compute kernels on different heterogeneous execution environments, we show that the use of standard C++ constructs as exposed by the HPX runtime system enables superb portability in terms of code and performance based on the real-world Octo-Tiger astrophysics application. We report our experience with porting Octo-Tiger to the ARM A64FX architecture provided by Stony Brook's Ookami and Riken's Supercomputer Fugaku and compare the resulting performance with that achieved on well established GPU-oriented HPC machines such as ORNL's Summit, NERSC's Perlmutter and CSCS's Piz Daint systems. Octo-Tiger scaled well on Supercomputer Fugaku without any major code changes due to the abstraction levels provided by HPX and Kokkos. Adding vectorization support for ARM's SVE to Octo-Tiger was trivial thanks to using standard C++
Conjugate variables approach to mixed $q$-Araki-Woods algebras: Factoriality and non-injectivity
Creators: name: Kumar, Manish
Publisher: name: arXiv
Year: 2023
Subjects: subject: Operator Algebras (math.OA)
subject: Functional Analysis (math.FA)
subject: FOS: Mathematics
subject: Primary: 46L36, Secondary 46L10, 46L53, 46L65

description: We establish factoriality and non-injectivity in full generality for the mixed $q$-Araki-Woods von Neumann algebra associated to a separable real Hilbert space $\mathsf{H}_{\mathbf{R}}$ with $\dim\mathsf{H}_{\mathbf{R}}\geq 2$, a strongly continuous one parameter group of orthogonal transformations on $\mathsf{H}_\mathbb{R}$, a direct sum decomposition $\mathsf{H}_{\mathbf{R}}=\oplus_{i}\mathsf{H}_{\mathbb{R}}^{(i)}$, and a real symmetric matrix $(q_{ij})$ with $q=\sup_{i,j}|q_{ij}|<1$. This is achieved by first proving the existence of conjugate variables for a finite number of generators of the algebras, following the lines of Miyagawa-Speicher and Kumar-Skalski-Wasilewski. The conjugate variables belong to the factors in question and satisfy certain Lipschitz condition.
description: 22 pages; Added a subsection on power series expansion of conjugate variables; To appear in Journal of Mathematical Physics
Circular polarization of the CMB: Foregrounds and detection prospects
Creators: name: King, Soma
name: Lubin, Philip
Publisher: name: arXiv
Year: 2016
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The cosmic microwave background (CMB) is one of the finest probes of cosmology. Its all-sky temperature and linear polarization (LP) fluctuations have been measured precisely at a level of deltaT/TCMB ~10^{-6}. In comparison, circular polarization (CP) of the CMB, however, has not been precisely explored. Current upper limit on the CP of the CMB is at a level of deltaV/TCMB ~10^{-4} and is limited on large scales. Some of the cosmologically important sources which can induce a CP in the CMB include early universe symmetry breaking, primordial magnetic field, galaxy clusters and Pop III stars (also known as the First stars). Among these sources, Pop III stars are expected to induce the strongest signal with levels strongly dependent on the frequency of observation and on the number, Np, of the Pop III stars per halo. Optimistically, a CP signal in the CMB due to the Pop III stars could be at a level of deltaV/TCMB ~ 2x10^{-7} in scales of 1 degree at 10 GHz, which is much smaller than the currently existing upper limits on the CP measurements. Primary foregrounds in the cosmological CP detection will come from the galactic synchrotron emission (GSE), which is naturally (intrinsically) circularly polarized. We use data-driven models of the galactic magnetic field (GMF), thermal electron density and relativistic electron density to simulate all-sky maps of the galactic CP in different frequencies. This work also points out that the galactic CP levels are important below 50 GHz and is an important factor for telescopes aiming to detect primordial B-modes using CP as a systematics rejection channel. Final results on detectability are summarized in Fig (11-13).
Curvature effects in the spectral dimension of spin foams
Creators: name: Jercher, Alexander
name: Steinhaus, Sebastian
name: Thürigen, Johannes
Publisher: name: arXiv
Year: 2023
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: It has been shown in [1] that a class of restricted spin foam models can feature a reduced spectral dimension of space-time. However, it is still an open question how curvature affects the flow of the spectral dimension. To answer this question, we consider another class of restricted spin foam models, so called spin foam frusta, which naturally exhibit oscillating amplitudes induced by curvature, as well as an extension of the parameter space by a cosmological constant. Numerically computing the spectral dimension of $1$-periodic frusta geometries using extrapolated quantum amplitudes, we find that quantum effects lead to a small change of spectral dimension at small scales and an agreement to semi-classical results at larger scales. Adding a cosmological constant $Λ$, we find additive corrections to the non-oscillating result at the diffusion scale $τ\sim 1/\sqrtΛ$. Extending to $2$-periodic configurations, we observe a reduced effective dimension, the form of which sensitively depends on the values of the gravitational constant $G$ and the cosmological constant $Λ$. We provide an intuition for our results based on an analytical estimate of the spectral dimension. Furthermore, we present a simplified integrable model with oscillating measure that qualitatively explains the features found numerically. We argue that there exists a phase transition in the thermodynamic limit which crucially depends on the parameters $G$ and $Λ$. The dependence on $G$ and $Λ$ presents an exciting opportunity to infer phenomenological insights about quantum geometry from measurement of the spectral dimension, in principle. [1]: S. Steinhaus and J. Thürigen, Emergence of Spacetime in a restricted Spin-foam model, Phys. Rev. D 98 (2018) 026013
description: 52 pages, 24 figures
Rural (In)Securities:
Creators: name: Jerónimo, Miguel Bandeira
Publisher: name: Leipziger Universitätsverlag
Year: 2017

description: Nach dem Ausbruch organisierter anti-kolonialer Gewalt während der frühen sechziger Jahre suchten portugiesische imperiale und koloniale Akteure nach politisch-militärischen Strategien, die Sicherheit, rudimentäre Sozialfürsorge und Entwicklung kombinierten. Diese speziische Kombination war ein Wesensmerkmal des Spätkolonialismus. Neben Strategien zur Bevölkerungskontrolle, „psychologischen Aktivitäten“ oder einer Sozialgesetzgebung entwickelte sich ländliche Entwicklungspolitik zu einem zentralen Instrument der spätkolonialen Sicherheitspolitik. Ausgehend von der Analyse zweier zentraler Dokumente, die ländliche Entwicklungspolitik propagierten, zeigt der Artikel, wie ländliche Regionen zu einem wesentlichen Austragungsort von militärisch-politischen Sicherheitsstrategien wurden, die viele Elemente ländlicher Entwicklungspolitik enthielten.
description: Comparativ, Vol 27 No 2 (2017): Rural Development in the Twentieth Century: International Perspectives